M-Block 351M/400
Parts Reference
Cast Iron Parts
Copyright © 2002-2003 Dave Resch
All rights reserved.
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This section lists Ford part numbers and casting ID codes for
the following
major cast iron parts of M-block (351M/400) engines:
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Engine blocks
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Cylinder heads
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Crankshafts
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Intake and exhaust manifolds
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Check out
this section
if you are not familiar with Ford part numbers and ID codes.
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Engine blocks
All 351M/400 engine blocks were cast at one of the following
foundries:
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Top: Four variants of the Cleveland Foundry code. Bottom:
Dearborn Iron
Foundry code (left) and Michigan Casting Center code (right).
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Cleveland Foundry
(casting code CF)
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Dearborn Iron Foundry
(casting code DIF)
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Michigan Casting Center
(casting code MCC)
In MY1971 through MY1972, engine blocks for 400s were cast
mostly
at the Dearborn Iron Foundry, with some cast at the Cleveland
Foundry.
After MY1972, all 351M/400 engine blocks were cast at either
the
Cleveland Foundry or the Michigan Casting Center.
The foundry casting code on all M-block engine blocks appears
at the
top rear of the block, behind the intake manifold, near the oil
pressure
sending unit hole.
Engine blocks from the Dearborn Iron Foundry and Michigan
Casting Center have the
casting date code next to the foundry code. Engine blocks from
the Cleveland
Foundry have the casting date code on the right side of the
block, near the block
casting ID code.
Foundry casting codes and date codes are significant for
M-block engine blocks
because some blocks that were cast before March 2, 1977 at the
Michigan Casting
Center are prone to water jacket cracking in the lifter valley
area. Blocks cast
at the Michigan Casting Center after that date do not have the
cracking problem.
To avoid the water jacket cracking problem, watch out for
engine blocks with the
Michigan Casting Center foundry mark and a date code of 7C02 or
earlier.
The following table lists M-block engine block part numbers and
casting ID codes.
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Model Year
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Part Number
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Casting ID
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Notes
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1971-1973
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D1AE-6010-A
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D1AE-A
D1AE-AC
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DIF or CF foundry code.
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1973
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D3AE-6010-B
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D1AE-A2C
D3AE-B
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Rare 400 w/ small-block bell housing. MCC foundry code.
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1974
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D4AE-6010-B
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D4AE-B1A
D4AE-B2A
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CF or MCC foundry code.
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1975-1979
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D5AE-6010-A
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D5AE-A
D5AE-AA
D5AE-A1A
D5AE-A2A
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CF or MCC foundry code. 351M/400 car only.
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1978-1979
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D8AE-6010-A
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D8AE-A
D8AE-AA
D8AE-A1A
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CF or MCC foundry code. Reinforced main webs. 351M/400 car
only.
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1977-1982
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D7TE-6010-A
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D7TE-A1A
D7TE-A2A
D7TE-A2B
D7TE-A3A
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CF or MCC foundry code. Reinforced main webs. 351M/400 truck
only.
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Cylinder heads
All M-block cylinder heads were cast at one of the following
foundries:
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Cleveland Foundry (casting code CF)
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Dearborn Iron Foundry (casting code DIF)
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Michigan Casting Center (casting code MCC)
Foundry codes and casting date codes on all M-block cylinder
heads are
located on the top of the head, usually on the intake runners.
You have
to remove the valve cover to see those codes.
Cylinder heads from the Dearborn Iron Foundry and Michigan
Casting Center
have casting ID codes on top of the intake runners. Cylinder
heads from
the Cleveland Foundry have casting ID codes on the bottom of
the intake
runners. You have to remove the intake manifold to see the
casting
ID codes on a CF cylinder head.
All 351C cylinder heads have a number “2” or “4” cast into the
upper corners
of the head. Those casting marks identify the head as either a
351C 2V or
351C 4V head. Early production (MY1971-MY1974) M-block cylinder
heads have
either no mark in that spot, or a “2” like the 351C 2V heads.
After the 1974 model year, all M-block cylinder heads cast at
the Cleveland
Foundry have an “M” cast into the top corners of the head. Some
M-block
cylinder heads cast at the Michigan Casting Center have
unmarked corners,
like early-production heads, and others have the “M” mark.
In later production ('75-up) M-block cylinder heads, there were
subtle design
differences (e.g., combustion chamber sizes) in cylinder heads
with
the same casting ID code. In some cases, the differences seem
to be related
to the foundry code, while others seem to be related to the
casting date.
M-block cylinder head combustion chamber sizes are listed in
the second
table below.
The following table lists M-block cylinder head part numbers
and casting
ID codes.
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Model Year
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Part Number
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Casting ID
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Notes
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1971
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D1AE-6049-A
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D1AE-A1A
D1AE-A1B
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Original 400 design.
No AIR passages.
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1971-1973
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D1AE-6049-A
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D1AE-A1C
D1AE-A2C
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Revised design w/ smaller chambers.
Used until mid-year '73.
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1973-1974
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D3AE-6049-G
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D3AE-G2B
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'73 mid-year change.
AIR passages drilled.
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1975-1979
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D5AE-6049-A
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D5AE-AA
D5AE-A1A
D5AE-A2A
D5AE-A3A
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All 351M/400 cars.
Chamber sizes vary from 74.5cc to 78.4cc.
More restrictive exhaust ports with "pot belly" valve boss.
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1977-1982
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D5AE-6049-A
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D5AE-AA
D5AE-A1A
D5AE-A2A
D5AE-A3A
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All 351M/400 trucks.
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The following table lists casting ID codes, production dates,
and combustion chamber sizes of M-block cylinder heads.
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Cylinder Head Casting ID
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Chamber Volume
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D1AE-A1A,A1B (1971 400)
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77.8cc
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D1AE-A1C,A2C ('71-'73 400)
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75.6cc
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D3AE-G2B (mid-year '73-'74 400)
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75.6cc
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D5AE-AA,A1A ('75-'76 351M/400)
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74.5cc
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D5AE-AA ('77-later 351M/400, CF)
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76.9cc
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D5AE-AA ('77-later 351M/400, MCC)
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78.4cc
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D5AE-A2A ('77-later 351M/400)
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74.5cc
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D5AE-A3A ('77-later 351M/400)
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74.5cc
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Crankshafts
Many people would like to know of an easy way to tell the
difference
between a 351M and a 400. Since the crankshaft is the main
component
that determines whether the engine is a 351M or a 400, the only
reliable way to identify an M-block engine as either a 351M or a
400
is to verify the crankshaft casting ID code. This requires, at a
minimum, removing the oil pan to view the crankshaft where the
casting ID code appears.
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Here’s
why you can’t distinguish a 351M from a 400 by inserting a
rod through
a spark plug hole to measure the stroke.
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Ford used the same components (engine blocks, cylinder heads,
manifolds,
etc.) to make both 351M and 400 engines. Therefore, you cannot
rely on the
casting ID codes or part numbers of any external component to
distinguish
a 351M from a 400.
Any 400 manufactured in any year can be rebuilt as a 351M by
simply
substituting the 351M crankshaft and pistons for the 400 parts.
Engine ID tags and calibration stickers are easily swapped from
one
engine to another, and even if they are not swapped, there is
no
way to tell whether an engine was rebuilt with 351M components
without looking at the crankshaft.
The following table lists M-block crankshaft part numbers and
casting
ID codes.
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Model Year
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Part Number
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Casting ID
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Notes
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1971
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D1AE-6303-A
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5M
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Original 400 crankshaft.
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1972-1973
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D2AE-6303-A
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5MA
5MAB
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400 crankshaft, car only.
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1974-1977
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D4AE-6303-B
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5MA
5MAB
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400 crankshaft, car only.
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1975-1976
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D5AE-6303-A
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1K
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Original 351M crankshaft.
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1977-1982
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D7AE-6303-A
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1KA
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All '77-up 351M car and truck.
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1977-1982
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D7TE-6303-A
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5MA
5MAB
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All '78-up 400 car and '77-up 400 truck.
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M-block crankshaft casting ID codes are located on either the
first
counterweight (opposite the first throw at the front of the
engine),
or on the side of the first throw. Casting ID codes are
recessed into
the unfinished (raw cast) surface. Sometimes the characters are
faint,
so you may have to thoroughly clean the area with a solvent to
find
the ID code.
All 351M and 400 crankshafts are interchangeable, as long as
you use the
corresponding pistons. You can use any 351M or 400 crankshaft
in any
M-block engine block. Main bearings are different for '77-up
truck blocks
(D7TE) and '78-up car blocks (D8AE).
Intake and exhaust manifolds
All M-block intake and exhaust manifolds were cast at one of
the
following foundries:
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Cleveland Foundry (casting code CF)
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Dearborn Iron Foundry (casting code DIF)
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Michigan Casting Center (casting code MCC)
Intake manifolds for early 400s (MY1971-MY1972) were cast
mostly at the Dearborn
Iron Foundry, with some cast at the Cleveland Foundry. After
MY1972, all M-block
intake manifolds were cast at either the Cleveland Foundry or
the Michigan Casting
Center.
Exhaust manifolds were cast at the Cleveland Foundry until the
end of MY1974. After
MY1974, M-block exhaust manifolds were cast at either the
Cleveland Foundry or the
Michigan Casting Center.
The following table lists M-block intake manifold part numbers
and casting
ID codes.
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Model Year
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Part Number
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Casting ID
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Notes
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1971
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D1AE-9424-A
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D1AE-9425-AC
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All 400.
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1972
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D2SE-9424-A
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D2SE-9425-AA
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All 400.
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1973-1974
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D3AE-9424-B
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D3AE-9425-BA
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All 400.
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1975
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D5AE-9424-C
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D5AE-9425-CC
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All 351M/400.
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1976
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D5AE-9424-C
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D5AE-9425-CD
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All 351M/400.
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1977-1979
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D7TE-9424-A
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D7TE-9425-JA
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All 351M/400, car and truck.
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1980-1982
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E0TE-9424-B
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D7TE-9425-SA
D7TE-9425-SB
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All 351M/400, truck only.
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The following table lists M-block exhaust manifold part numbers
and casting
ID codes.
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Model Year
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Part Number
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Casting ID
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Notes
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1971-1974
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D1AE-9431-A (left)
D1AE-9430-A (right)
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D1AE-A
D1AE-AA
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All 400.
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1975-1979
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D5AE-9431-A (left)
D5AE-9430-A (right)
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D5AE-A
D5AE-AB
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All 351M/400 cars.
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1977-1982
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D5AE-9431-A (left)
D7TE-9430-A (right)
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D5AE-A
D5AE-AB
D7TE-A
D7TE-AB
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All 351M/400 truck.
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Although 351C 2V exhaust manifolds are interchangeable with
M-block exhaust
manifolds, Ford designed separate manifolds for the 400. This
was probably
because the 400’s taller deck height made it larger and wider
than the 351C.
All M-blocks from '71 to '82, both car and truck engines, use
the same
type of exhaust manifold on the driver’s side (left). All
M-block car engines
from '71 to '79 use a car-only exhaust manifold on the
passenger side (right).
When the M-block was introduced in trucks in MY1977, the
narrower truck chassis
required the passenger side (right) exhaust manifold to be
redesigned so that
the manifold’s lower flange would clear the frame rail. All
351M and 400
truck and van engines from '77 to '82 use a truck-only exhaust
manifold
on the passenger side (right).
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