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1968 - 1982 Corvette Transmission Identification Codes


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1968 Transmission Identification Codes

S Saginaw 3-Speed
P Muncie 4-Speed
K Turbo Hydra-Matic 400, Corvette 327 Engines
L Turbo Hydra-Matic 400, Corvette 427 Engines

1969 Transmission Identification Codes

S Saginaw 3-Speed
P Muncie 4-Speed
A* Muncie 4-Speed M20 Wide-Range (2.52:1 1st gear)
B* Muncie 4-Speed M21 Close-Range (2.20:1 1st gear)
C* Muncie 4-Speed M22 Close-Range (2.20:1 1st gear) Rock Crusher
K Turbo Hydra-Matic 400, 350 Cubic-Inch Corvette Engines
L Turbo Hydra-Matic 400, 390 & 400 Horsepower Corvette Engines
Y** Turbo Hydra-Matic 400, Corvette 430 & 435 Horsepower Engines

* Suffix codes added to build date codes of Muncie transmissions for identification purposes effective October 21, 1968.  Note:  The nomenclature "rock crusher" was actually used by Chevrolet.

** High Shift Point Transmission.

1970 Transmission Identification Codes

P Muncie 4-Speed, Heavy-Duty Aluminum case
A* Muncie 4-Speed M20 Wide-Range (2.52:1 1st gear)
B* Muncie 4-Speed M21 Close-Range (2.20:1 1st gear)
C* Muncie 4-Speed M22 Close-Range (2.20:1 1st gear) Rock Crusher
K Turbo Hydra-Matic 400, 350 Cubic-Inch Engines
S Turbo Hydra-Matic 400, 454 Cubic-Inch Engines
Y** Turbo Hydra-Matic 400, 454 Cubic-Inch Engines

* Suffix codes added to build date codes of Muncie transmissions for identification purposes.

** High Shift Point Transmission believed scheduled for use with the 1970 LS7 engine which was not available for retail sale.

1971 Transmission Identification Codes

P Muncie 4-Speed, Heavy-Duty Aluminum case
A* Muncie 4-Speed M20 Wide-Range (2.52:1 1st gear)
B* Muncie 4-Speed M21 Close-Range (2.20:1 1st gear)
C* Muncie 4-Speed M22 Close-Range (2.20:1 1st gear) Rock Crusher
K Turbo Hydra-Matic 400, 350 Cubic-Inch Engines
S Turbo Hydra-Matic 400, 454 Cubic-Inch Engines
Y** Turbo Hydra-Matic 400, 454 Cubic-Inch LS6 Engine

* Suffix codes added to build date codes of Muncie transmissions for identification purposes.

** High Shift Point Transmission.

1972 Transmission Identification Codes

P Muncie 4-Speed, Heavy-Duty Aluminum case
A* Muncie 4-Speed M20 Wide-Range (2.52:1 1st gear)
B* Muncie 4-Speed M21 Close-Range (2.20:1 1st gear)
C* Muncie 4-Speed M22 Close-Range (2.20:1 1st gear) Rock Crusher
K Turbo Hydra-Matic 400, 350 Cubic-Inch Engines
S Turbo Hydra-Matic 400, 454 Cubic-Inch Engines

* Suffix codes added to build date codes of Muncie transmissions for identification purposes.

1973 Transmission Identification Codes

P Muncie 4-Speed, Heavy-Duty Aluminum case
A* Muncie 4-Speed M20 Wide-Range (2.52:1 1st gear)
B* Muncie 4-Speed M21 Close-Range (2.20:1 1st gear)
CK Turbo Hydra-Matic 400, 350 Cubic-Inch L48 Engine
CY Turbo Hydra-Matic 400, 350 Cubic-Inch L82 Engine
CS Turbo Hydra-Matic 400, 454 Cubic-Inch Engine

* Suffix codes added to build date codes of Muncie transmissions for identification purposes.

1974 Transmission Identification Codes

P Muncie 4-Speed, Heavy-Duty Aluminum case
A* Muncie 4-Speed M20 Wide-Range (2.52:1 1st gear)
B* Muncie 4-Speed M21 Close-Range (2.20:1 1st gear)
W Warner 4-Speed, Heavy-Duty Aluminum case
CK Turbo Hydra-Matic 400, 350 Cubic-Inch L48 Engine
CZ Turbo Hydra-Matic 400, 350 Cubic-Inch L82 Engine
CS Turbo Hydra-Matic 400, 454 Cubic-Inch Engine

* Suffix codes added to build date codes of Muncie transmissions for identification purposes.

1975 Transmission Identification Codes

W Warner 4-Speed, Heavy-Duty Aluminum case
CK Turbo Hydra-Matic 400 with L48 Engine
CZ Turbo Hydra-Matic 400 with L82 Engine

1976 Transmission Identification Codes

W Warner 4-Speed, Heavy-Duty Aluminum case
AM, XH Turbo Hydra-Matic 350 with L48 Engine
CZ Turbo Hydra-Matic 400 with L82 Engine

1977 Transmission Identification Codes

W Warner 4-Speed, Heavy-Duty Aluminum case
AM Turbo Hydra-Matic 350 with L48 Engine
CB Turbo Hydra-Matic 400 with L82 Engine

1978 Transmission Identification Codes

S6 Warner 4-Speed, Aluminum case, Wide-Ratio (2.85:1 1st gear)
ZU Warner 4-Speed, Aluminum case, Wide-Ratio (2.64:1 1st gear)
ZW Warner 4-Speed, Aluminum case, Close-Ratio (2.43:1 1st gear)
5WB Turbo Hydra-Matic 350
5TL Turbo Hydra-Matic 350

1979 Transmission Identification Codes

UH Warner 4-Speed, Aluminum case, Wide-Ratio (2.64:1 1st gear)
UK Warner 4-Speed, Aluminum case, Close-Ratio (2.43:1 1st gear)
TB Turbo Hydra-Matic 350
WB Turbo Hydra-Matic 350

1980 Transmission Identification Codes

ZJ Warner 4-Speed, Aluminum case, Wide-Ratio (2.88:1 1st gear)
JC Turbo Hydra-Matic 350, with 305 California Engine
TW Turbo Hydra-Matic 350,  with 350 Engine

1981 Transmission Identification Codes

CC Warner 4-Speed, Aluminum case, Wide-Ratio (2.88:1 1st gear)
8JD Turbo Hydra-Matic 350

1982 Transmission Identification Codes

YA Turbo Hydra-Matic 700-R4, 4-Speed Automatic with Overdrive

Transmission Production Code Locations

3-Speed - 1968-1969: Stamping located on the machined surface on the left side of case, just below and rear of cover.

Muncie 4-Speed - 1968 through mid-1974:  Stamped vertically on the right side of the case at lower rear, just ahead of the transmission extension.

Warner 4-Speed - Mid-1974 through 1981:  Stamped at the left side on the top rear of the case.  The 1974-77 Warner 4-Speed may also have a two-digit code painted on the left side of the case below the side cover to identify the low gear ratio:

HS = 2.64:1(Wide ratio)

HW = 2.43:1(Close ratio)

Turbo Hydra-Matic 400 - 1968-1977:  Located on the plate attached to the vertical surface of the transmission case above the right-gear corner of the oil pan.

Turbo Hydra-Matic 350 - 1976-1981:  Code stamping located on the right-hand vertical surface of the transmission oil pan.

Turbo Hydra-Matic 700R4 - 1982:  Code stamping located in the case on the right-hand side of the oil pan rail.

Unit Serial Number Identification

Saginaw 3-speed & Muncie 4-speed

The method of unit production serial coding for 1968-69 Corvette 3-speed and 1968-74 Muncie 4-speed manual transmissions is the prefix code as listed, followed by the last digit of the vehicle model-year; a letter representing the month of transmission manufacture (see month chart); followed by two digits designating the date of the month ("01" through "31" ), ending with the applicable Muncie gear ratio suffix.

Warner 4-speed:  Code begins with source code "W"; followed by month (see chart); day of the month; followed by the last digit of the calendar year; ending with the shift produced code ("1" 1st shift; "2" 2nd).

Turbo Hydra-Matic 400:  For quick identification, the modulator assembly is located in the right front area of the transmission.  The Code Number stamped on the tag will begin with the last two digits of the vehicle model year; vehicle and engine type code from chart; ending with three digits representing a modified Julian calendar date of manufacture code.  This build date code begins with the Julian date (day of the year) on which model-year production started.  If production started on August 21st, the build date code would be "233" (or "234" during leap year) through "365" or ("366") for December 31st.  The sequence then continues until the end of the model production year.  Therefore a build date code of  "385" or ("386") would be January 20th (365 + 20 = 385).  Below the Code Number stamping can be found The Transmission Serial Number.

Turbo Hydra-Matic 350:  For quick identification, the modulator assembly is located at the rear of the transmission case.  The THM 350 code number stamping contains the source ("B" for Parma, "Y" for Toledo, or "J" for GM Canada), a single digit for the model year ("6" for 1976), a letter representing the month (see chart), and day produced ("01" through "31" ) ending with the shift produced code ("D" or "N").

Turbo Hydra-Matic 700R4:  This 1982 transmission stamping would begin with a "9" (nine) for the 1982 model-year, followed by the vehicle application code "YA", then a three-digit build date code representing the Julian calendar date, ending with a "D" or "N" for work shift produced.

Calendar Month Codes (Muncie & Turbo Hydra-Matic)

                   A - January               E - May             P - September

                       B - February             H - June            R- October

                       C - March                   K - July             S - November

                       D - April                     M- August        T - December

Calendar Month Codes (Warner)

                   A - January               E - May             J - September

                       B - February             F - June            K- October

                       C - March                   G - July             L - November

                       D - April                     H- August        M - December

Note:  In addition to the transmission unit serial number codes described, Chevrolet added a (hidden) vehicle identification serial number (VIN) derivative stamping to each transmission installed in a Corvette at the Assembly plant, in much the same manner as that used for engines.  This number was often stamped near the production code on manual transmissions; either on the raised boss on the right forward side of the case or on the left side lip of the bell housing flange on automatic transmissions.