Gm Transmission Identification



Chevy Transmission Identification and Decoding
  1. Gm Transmission Identification Codes
  2. How To Identify A Gm Transmission
  3. Gm Automatic Transmission Identification
  4. Gm Transmission Identification 3885010

Automatic transmissions Early models. The GM Hydra-Matic was a success and installed in the majority of GM models by 1950. Through the 1950s, all makers were working on their own automatic transmission, with four more developed inside GM alone.

  • GM Transmissions: GM Power Glide 2 Speed Transmission. GM Turbo 200 and 200C: 3 Speed Transmission. GM Turbo 2004R (2004R Transmission) Overdrive Transmission. GM Turbo 350 and 350C (TH350 Transmission) 3 Speed Transmission. GM Turbo 400 TH400 Transmission 3 Speed Transmission. GM 700R4 (4L60) not 4L60E shown below.
  • Model Year Engine Trans Type Transmission; Astro: 1989-1992: TH700-R4/4L60: Astro: 1993 - Up: 4L60-E: Astro Van, Safari: 1995-06: V6 4.3L: 4 Spd RWD/4X4: 4L60E.

General Chevrolet Transmission Identification

Transmissions are marked and identified by:

- Casting numbers on the case, extention housing and side cover
(on manual trans).
- Date Casting Codes
- Assembly Date Code Stamping - can be stamped anywhere..
- Chassis Vin Number stamping - beginning in 1962

Transmissions have RPO numbers, usually beginning with 'M'.
This page covers automatic trannies. Go here for Chevy Manual Transmission Identification.

Chevrolet Automatic Transmission Identification & Description

Automatic transmission types are generally identified by their pan shape.


The THM200 and the THM250 have pans shaped like a THM350, HOWEVER, the THM200 will have the words HYDRAMATIC DIV. and METRIC stamped into the pan.

Chevy Automatic Transmission Description & Usage
THM200 - Light duty, 'metric' 3 speed transmission.

THM250 - Used in small 4 cylinder cars (Vega, Sunbird, Monza) from 1973 to 1981 and some Nova/Camaro/Chevelle 6 cylinders in 1974 & 75. The 4 cylinder models have 4 large cooling holes near the torque converter, while on the 'bigger cars' there are no cooling holes.

THM200-R4 - Used in GM rear wheel drive cars with the 3.8 V6, 305 & 350 Olds and 301 pontiac from 1981 to 1989. This is a 4 speed, overdrive unit.

THM350 - Medium duty 3 speed trans used from 1969 to 1989, Used in Buick, Olds, Pontiac and Chevrolet cars and Chevy & GMC light trucks until 1987. Generally used in straight and V6 and small block engines. Generally able to handle up to 400 foot pounds of torque.

Punjabi wedding tappe mp3. THM375B Abhineta ki taiyari book pdf. - This trans is identical to the THM350, but is considered a heavier duty transmission.

THM375 - This transmission is a derivative of the THM400 sharing the external appearance of the 400. It'll be marked 375-THM on the bottom of the tailshaft housing. It's a light duty version of the THM400, has ABSOLUTELY NO RELATION to the THM375B, and was found in 1972 to 1976 full-size cars. The Turbo 375 was modified to accept the Turbo 350 driveshaft yoke.

THM400 - The THM400 was GM's Heavy-duty 3 speed transmission used from 1964 to 1990. Used on large displacement, high torque engines and engines with towing packages. Generally found in Chevy & GM trucks, cadilacs and large displacement engined, full size GM rear wheel drive cars.

THM700-R4 - 4 Speed transmission used in GM cars and light trucks with the 2.8, 3.1, 4.3, V6, Chevrolet built 305, 350 and 454 engines from 1982 to 1992.

4L60 - Early 1990's saw the 700R4 renamed to the 4L60, and 'electronic' models were named 4L60E. 4L60 means 4 forward speeds, L = longitudily mounted (rear wheel drive). 60 is the strength rating (less than the 4L80).

3L80 - The 3L80 is a renamed THM400, used in the early 1990's. The 3L80HD would be the THM475 (heavy duty unit).

4L80 - An overdrive model of the THM400. The 4L80E would be the 'electronic' model.

Transmissions with a suffix of 'C' on the end of the type (THM200C) indicate the transmission has a lock up torque converter.

Chevy Automatic Transmission Identification: Other Methods

Some transmissions have a code stamped onto them. Others have a tag rivited to the case.

Most transmissions will have a 'source serial number' (chassis vin) usually found close to the transmission code. This number will contain division ID #, model year, assembly plant and production sequence (last 6 digits) of the VIN stamped onto the transmission. Example: 19N500001. The source serial number is from the CAR the transmission originally went into, NOT the assembly plant.

Location of source serial number

On the THM350, the VIN will be stamped on either the drivers side housing near the shifter, on the right side of the housing just above the pan, or on a boss behind the bellhousing flange on the passenger side of the transmission.

On the THM400 the VIN is stamped on a machined surface just above the pan on the drivers side.

On the THM200-R4 the VIN is stamped onto the housing towards the rear of the pan, on the drivers side.

On the THM700-R4 the VIN is either stamped onto a boss behind the bellhousing flange on the passenger side, just above the pan on the drivers side, or just behind the governor cover, stamped vertically where the case meets the tailshaft housing.

Gm Transmission Identification Codes

Prior to 1967, transmission ID numbers contained the plant prefix code, month and date of production (expressed numerically) and a shift code (D = Day, N = Night). From 1967 on, the ID number contained the transmission type or plant prefix, Date (coded below) and a shift code. The constants in decoding the trans ID number are the date the transmission was produced.

Pre-67 Example: C213N - (C = Cleveland Powerglide, February 13, Night Shift)
Post-67 Example: P9E03 - (P = TYPE, 9 = year (1969), E = Month, 03 = Day of Month)

Gm Transmission IdentificationGm Transmission Identification

Month code: (NOTICE this is NOT in alphabetic order)
A = Jan, B = Feb, C = Mar, D = Apr, E = May, H = Jun, K = Jul, M = Aug, P = Sep, R = Oct, S = Nov, T = Dec

The dropbox contains Camaro transmission codes. What SHOULD have been installed, or what was offered for the year selected.

How To Identify A Gm Transmission

Transmission

Gm Automatic Transmission Identification


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Gm Transmission Identification 3885010

Last updated: 10/20/2011
Author: MadMike Maciolek


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