Engine Stamping Decoding

Engine Stampings

Decoding Vehicle Serial Number on the Engine
Starting in 1958, all engine and major driveline components are stamped with the Vehicle ldentification Number (VIN) as a theft deterrent. During the first two years (until 1970), Chrysler usually stamped the entire number on the rail. From 1970 on, they stamped only the last eight digits on the engine. Slant-Bkengrnes have this number stamped below the cylinder head on the passenger side of the block. V8 engines are stamped on the driver's side upper rear ofthe block in 1968, and above the passenger side oil pan rail near the motor mount on 1959-and—later4engrnes. Most warranty engines will not have this stamping (although the technicians were supposed to restamp them after replacement).


1968-74 Vehicle Assembly Plant Codes
A = Lynch Road, Detroit, Ml `
B = Dodge Main, Hamtramck, Ml
C = Jefferson Avenue, Ml
D = Belvidere, lL
E = Los Angeles, CA (1968-71)
F = Newark, DE
G = St. Louis, MO
H = New Stanton, PA (1970-71)
P = Export (1968)
R = Windsor, Ontario

Engine Serial Number
The serial number is a sequence of 14 digits that contains a wealth of information all in one location. A few problems must be answered hrst, such as where it is found and what it means. Occasionally, for whatever reason, an engine will not have a serial number stamped on it. This seems to be fairly common, so if yours doesnt, it's not that big of a deal. On slant—6 engines the number is stamped on the block, below the head near the ignition coil. Small blocks seem to have their own story—a sequence of numbers will almost always be present, but they don't always follow this particular serial number pattern. For small blocks, look on the front face of the block, below the driver's side cylinder head (see the small—block ID Boss explanation for more information). For B and RB big blocks, the number is typically found along the oil pan rail, close to or under the starter. These are hand—stamped numbers, so visibility and consistency are not always the greatest.

Characters 1-2  = Plant lD code.
Characters 3-5 = Cubic inch displacement
Character 6 = Additional build information (mostly letters)
Characters 7-10 = 10,000 day calendar date
Characters 11-14 = Engine production number that cycle

NOTE : There may be other characters after these, but they have not been decoded and do not appear to be meaningful to restorers atthis time.

Engine Stampings
The easiest way to determine what engine youre looking at is by locating and decoding the stampings on the I0 boss. This machined pad includes the displacement, build date, and other special information relating to that particular engine. The information on the pad is hanclstamped and may be difhcult to read without cleaning the area. But, since this is the simplest way to identify various Chrysler engines, it's worth the trouble. The location ofthe pad varies on small block, "B" and “RB" engines, and they're listed below.

Small Block ID Boss
Small Block: Locating the ID pad on a small block is the simple part—decoding the information is where it gets tricky. The pad is found on the drivers side front of the block below the cylinder head on both "A" and "LA" small blocks. With the engine in the car and all the accessories in place, it may be hard to see, but it's there.


Secondary Codes
Here is a listing ofthe additional, or secondary, information codes and their meanings. These are found on the ID boss or sequence number of your engine. In the case of small blocks, some of these symbols might be found on the affected part (the symbole on the tappet boss; anything crank related is on the No, 8 counterweight). Although this list is as complete as we can make it, there may be other codes or symbols not listed here. ID boss decoding is an ongoing project and new information is occasionally found.

T  = Truck
R  = Regular Fuel
P  = Premium Fuel
LC = Low Compression
HC = High Compression
MP = Maximum Performance
HP, HP2 = High Performance
X  = .001" Undersize Crank
X  = .U10" Undersize Crank
Diamond = .008" Oversize Tappets
OS = .0O5" Oversized Valve Guides
X  = Oversize Valve Guides
S  = Special Engine (possibly warranty)
SP = Special Engine (TA340 or police)
WT = Water Tested
H  = Hemi (before displacement: H425)
A  = .02U" Oversize Cylinder Bore
B  = .010" Underslze Main and Rod Bearings
E  = Cast Crank
H  = Standard 4-bbl V8

B/RB Big Block and Hemi ID Boss
Big Block: Locating the lD pad on big blocks is the easiest way to distinguish a "B" engine from an "RB" engine. On "B" engines, the lD pad is located on the passengers side of the engine, just below the cylinder head next to the distributor base; on "RB" or Hemi engines, the lD pad is located on top ofthe block directly infront of the intake manifold valley pan, next to the distributor base toward the driver's side,


Model Year
The following is a list of letter codes and their corresponding years. The year always precedes the engine displacement.
P = 1950
R = 1961
S = 1962
T = 1953
V = 1964
A = 1955
B = 1955
C = 1957
D = 1968
E = 1969
F = 1970
G = 1971
H = 1972
J = 1973
K or 4 = 1974
L or 5 = 1975
M or 6 = 1976
N or 7 = 1977

Assembly Plant Codes
K = Toluca
M or PM = Mound Bd.
MV or MN = Marysville
T or PT = Trenton
W = Windsor