Troubleshooting Diagnosis of Cars Computers and 21st Century Living.

GM General Motor Transmission Codes Identification



Identification is by a combination of the letter code and year designation which precedes the transmission serial number of

the production code number. In some instances the year designation precedes the letter code; in others it follws the letter

code. Beginning in mid 1986 some automatic transmission codes were switched from a two letter code to a three letter

code. The number preceding all three letter codes designates model year. The third letter of a three letter code designates

which type of transmission it is.

These codes can be found on various parts of the transmission.

Some of these locations are listed below.

1. Stamped on the servo cover.

2. Stamped on a metal tag fastened to the transmission case.

3. Stamped on governor cover.

4. Ink stamped on case.


(1) (2) (3) (4)

(1) Model Year

(2) Transmission Code

(3) Date Built

(4) Shift Built

(1) Model Year

0 ’80 ’90

1 ’81 ’91

2 ’82 ’92

3 ’83 ’93

4 ’74 ’84 ’94

5 ’75 ’85 ’95

6 ’76 ’86 ’96

7 ’77 ’87 ’97

8 ’78 ’88 ’98

9 ’79 ’89 ’99

(2) Transmission Code

(The 3rd letter – example: M – designates

this unit as a 700R4 or a 4L60 transmission)

3rd letter trans type option

A 400 or 3L80 M40

B 200C MV9

4T65E M15

4T65E MN3

4T65E MN7

C 125C or 3T40 MD9

D 4L60E M30

E 4L30E ML4

F 200 4R MW9

H 440 T4 or 4T60 ME9

M 700 R4 or 4L60 MD8

N 4T80E MH1

P R2 or 4L80E MT1

R 4T40E MN4

S 125C or 3T40-A MD9

W 4T60E M13

Z F-7 ME9

NOTE: Transmission for model years 1990-91 will carry the old

designation codes along with the new HYDRA-MATIC designation

codes. Beginning with the model year 1992 only the HYDRA-MATIC

designations will be used.

New style HYDRA-MATIC trans type example:

3 T 40 E

Number of Speeds Type Series Major Features

3 T-Transverse Based on relative E-Electronic Controls

4 L-Longitudinal Torque Capacity A-All Wheel Drive

5 HD-Heavy Duty


(3) Date Built

182=June 30th

(4) Shift Built

A & B=First Shift

C & H=Second Shift


35 Responses

  1. 74 CK 18596 This is on an ID tag riveted to the side of a THM 400. I cannot find a break down on how to identify this transmission. There is also a number, 535 above this number. Please help me with identifing this transmission.
    What I was told, it came out of a Corvette, but this is all I know about it.
    Thanks in advance for your help. You can contact me via the email address below.

    December 2, 2012 at 8:58 am

    • admin

      1974 Chevy Corvette “CK”=
      1974 Corvette 350CU V8………………….(210hp to 300hp)…Corvette…

      December 2, 2012 at 5:01 pm

  2. Charles o

    CA-66. 3658

    CFD 24

    December 14, 2013 at 4:50 pm

    • admin

      how bout a pic of the housing and the oil pan?

      December 26, 2013 at 3:10 pm

  3. dusty

    165 on top of tag then 89 1 ba 19230 please help withe type trans

    December 25, 2013 at 9:16 pm

    • admin

      I need a picture of the oil pan and the overall trans to be more helpful

      December 26, 2013 at 3:12 pm

  4. Jacob Wooten

    assuming this is a turbo 350 based on pan shape. this number is stamped on the passenger side towards the front of the bellhousing. ces156898

    December 28, 2013 at 7:16 pm

  5. Troy Cryer

    I have a 4L60E with code DC JD266V. Or at least the first digit looks to be a D…I guess it could be a 0. It says M30 on the drivers side and has the Green electronic connector on the passenger side. I am trying to determine the correct year so I can order the right wiring harness as this one is leaking from the center of the connector (not around the side due to the O-ring. Any assistance would be appreciated.

    January 7, 2014 at 2:39 pm

    • admin

      there are several possibilities, the biggest and most likely from my decoding is:
      1993 or 1994 Chevy Pickup 5.7 or 1993-1994 Astrovan

      January 7, 2014 at 3:15 pm

  6. Troy

    What makes you think it is a ’90s unit? Could it not be a 2004? I was told it was an ’04 or ’05 unit when I purchased it. What additional information do you need to clarify? It does have a step pan which I thought was only introduced after 1998/1999.

    January 7, 2014 at 3:29 pm

    • admin

      ok if you were told it was a 04 05
      both use a *CJD*** three letter code.
      do you have the 8 or so digit serial code?

      January 7, 2014 at 3:43 pm

      • Troy

        yes, the serial number is 26215822

        January 7, 2014 at 3:55 pm

  7. admin

    one piece bell housing or unbolt bell housing?

    January 7, 2014 at 3:35 pm

  8. Troy

    unbolt. It also has the LS bolt pattern on top of the bell housing (single top bolt hole).

    January 7, 2014 at 3:38 pm

  9. Troy

    yes,…that’s what I was trying to explain about the LS bolt pattern.

    January 7, 2014 at 3:41 pm

  10. admin

    If your code its actually begins with a zero past coding would date that as a model year 200(0) ’00’ not an 04.
    the first letter is numally a number indicating the last digit of the year.
    DC JD266V becomes 0 cjd 266 v
    2000 4l60e

    January 7, 2014 at 3:54 pm

  11. admin

    Ok the results are in it is a 2000 silverado 2WD 5.3 from an extended cab truck.
    GM 24216074 ’00
    Ident: 0CJD ’00
    sorry it took so long to have an exact reply.

    January 7, 2014 at 3:58 pm

    • Troy

      Thank you. I appreciate the help.

      January 7, 2014 at 4:02 pm

  12. admin

    Anytime, I learned a few new tricks today also, thanks.

    January 7, 2014 at 4:03 pm

  13. I have a 400 hydromatic the metal plate on passenger side says 72-cm 1202 what did this this transmissions come out of a little help please

    September 11, 2014 at 8:10 pm

    • admin

      1972 Chevrolet El Camino 307 cu V8

      September 18, 2014 at 10:57 pm

  14. woodie

    I have code 8YPM243A also has MD8. Guessing it is 88 4L60?

    September 22, 2014 at 6:47 pm

    • admin

      yeah pretty much, it decodes on my end as a 1988 Chevy th700r4 from a 305CU 5.0 engine
      maybe a Camaro/Firebird if the tailhousing has the sideways bolt holes for the torque bar its CAMARO/FIREBIRD if not
      its probable Chev Truck or Caprice.

      September 23, 2014 at 1:07 pm

  15. jim

    I have a trans someone told me is a turbo 350 i wanna nake sure it c6b136403 help me out here

    November 14, 2014 at 2:01 pm

    • admin

      more info or recheck the numbers? somethings missing on this.

      January 21, 2015 at 2:27 pm

  16. sam

    I have a 400 turbo with a code 90 – fpa – 2715. I’d like to know what it came out of?????????

    November 19, 2014 at 9:45 am

    • admin

      the best I can decode is 1990 Chev c1500 pickup 2WD.

      January 21, 2015 at 2:23 pm

  17. nick

    Hey I need some help identifying a th400 the #s on the riveted tag are 492 on top of the tag and #s below it r 76-cz-3574 any help would b great thanks for your time

    December 7, 2014 at 6:49 am

    • admin

      that’s a corvette 1976
      1976 Corvette Transmission
      Code Transmission
      CZ Turbo Hydra-Matic 400 with 350 L-82 Engine.
      Hope it helps.

      January 21, 2015 at 2:10 pm

  18. Matt

    I have a TH 400 trans. The numbers on the riveted tag are 79-of 27260. The bellhousing won’t bolt up to my 86 350 g10 van motor. Thinking it’s Oldsmobile and want to use an adapter, but don’t know which one to get any help identifying the trans would be greatly appreciated.

    March 8, 2015 at 1:06 pm

    • admin

      Quickreference indicates that as a 1979 Cadillac.
      more info (tailshaft length) or pics and I might be able to get closer.
      But to answer the big concern the bell housing pattern is the same for that trans whether it came from
      a Olds, Buick, Cad or Pontiac- only the Chevy uses a different bell pattern. The others are identical.
      Hope it helps

      March 13, 2015 at 9:06 am

  19. eric

    I have a transmission I’m having trouble decoding. The number is… 7TX1-Y-00520152-240B

    April 16, 2015 at 6:02 pm

    • admin

      With more info I might be able to help.
      make model year or best guesstimate?

      April 17, 2015 at 10:08 am

  20. JesseFrazier

    I have a 5 speed with #s GM18672305 anybody have a clue what this is to

    April 21, 2015 at 7:09 am

    • admin


      April 21, 2015 at 11:29 am

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