Chevrolet Transmission

Chevy Transmission Identification and Decoding

Chevrolet Transmission R700
Chevrolet Transmission Service
Chevrolet Transmission Identification

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.

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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.

THM375B Aol for mac os. - 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.

Virus removal for mac. 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.

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)

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.

The latest posts on transmissions from the NastyZ28 message board. Please join in the discussion by registering here.

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

Return to Main Decoding Page

Dimension 'C' is the distance from the bellhousing to the center of the transmission mounting pad. Note: The mounting pad is usually a part of the extension housing, but the graphic shows it on the maine case. this means that dimension 'C' is usually longer than dimension 'B'.

Chevrolet Transmission R700

Powerglide (bellhousing pattern - Chevrolet, Fit-all)

Style	A		B		C		D		E
Short shaft	25 23/64'	644,1 mm	16 5/16'	414,3 mm	20 9/16'	522,3 mm	3 3/4'	95,3 mm	19'	482,6 mm
Shorty	17 15/16'	439,7 mm	16 5/16'	414,3 mm	20 9/16'	522,3 mm	N/A	N/A	19'	482,6 mm
Long shaft	27 9/16'	700 mm	16 5/16'	414,3 mm	20 9/16'	522,3 mm	3 3/4'	95,3 mm	19'	482,6 mm

TH350 (bellhousing pattern - Chevrolet, BOP, Fit-all)

Style	A		B		C		D		E
6' tailshaft	27 11/16'	703,3 mm	21 5/8'	549,3 mm	20 3/8'	517,5 mm	3 3/4'	95,3 mm	19 1/8'	485,8 mm
9' tailshaft	30 11/16'	779,5 mm	21 5/8'	549,3 mm	20 3/8'	517,5 mm	3 3/4'	95,3 mm	19 1/8'	485,8 mm
12' tailshaft	33 27/32'	859,6 mm	21 5/8'	549,3 mm	20 3/8'	517,5 mm	3 3/4'	95,3 mm	19 1/8'	485,8 mm

TH400 (bellhousing pattern - Chevrolet, BOP)

Style	A		B		C		D		E
4' tailshaft	28 3/8'	720,7 mm	24 5/16'	617,5 mm	26 15/16'	684,2 mm	4 1/4'	108 mm	20'	508 mm
9' tailshaft	33 27/32'	859,6 mm	24 5/16'	617,5 mm	27 15/16'	709,6 mm	4 1/4'	108 mm	20'	508 mm
13' tailshaft	37 7/8'	962,0 mm	24 5/16'	617,5 mm	27 21/32'	702,5 mm	1 3/4'	44,5 mm	20'	508 mm

TH200-4R (bellhousing pattern - BOP, Fit-all)

Style	A		B	C		D		E
All	27 11/16'	703,3 mm	integral tailhousing	27'	685,8 mm	3 3/4'	95,3 mm	19 1/8'	485,8 mm

TH700-R4 /4L60 (bellhousing pattern - Chevrolet)

Style	A		B		C		D		E
All except Corvette	30 3/4'	781,1 mm	23 3/8'	593,7 mm	22 1/2'	571,5 mm	3 3/4'	95,3 mm	20'	508 mm
Corvette (1982-1992)	29 7/8'	759 mm	23 3/8'	593,7 mm	22 1/2'	571,5 mm	3 3/4'	95,3 mm	20'	508 mm
With Th350 6' tailshaft	29 1/2'	749,3 mm	23 3/8'	593,7 mm	22 1/2'	571,5 mm	3 3/4'	95,3 mm	20'	508 mm
* See note	30 1/2'	774,7 mm	23 3/8'	593,7 mm	28'	711,2 mm	3 3/4'	95,3 mm	20'	508 mm

* An extension housing p/n 8673406 (old p/n 24214689) is available for the TH700R4/4L60 transmission that moves the rear transmission mount to the same position as a TH400 (short-style 4' tail) or TH200-4R transmission. This 7-3/8' long extension housing can eliminate transmission crossmember modifications when replacing a TH400 or TH200-4R transmission with a 4L60 assembly.

4L60E (bellhousing pattern - Chevrolet/removable)

Style	A		B		C		D		E
All 1993-'95 exept Corvette	30 3/4'	781,1 mm	23 3/8'	593,7 mm	22 1/2'	571,5 mm	3 3/4'	95,3 mm	20'	508 mm
Corvette, 1993-'95	29 7/8'	759 mm	23 3/8'	593,7 mm	22 1/2'	571,5 mm	3 3/4'	95,3 mm	20'	508 mm
Corvette (transaxle) 1996-up	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
All 1996-up exept Corvette and LS1	30 3/4'	781,1 mm	21 3/4'	552,5 mm	23 3/16'	589 mm	3 3/4'	95,3 mm	18 1/4'	463,6 mm

4L60E / 4L65E (w/ removable bellhousing) All LS1 Type

Style	A		B		C		D		E
LS1, 1998-up	31 5/32'	791,4 mm	21 3/4'	552,5 mm	23 19/32'	599,3 mm	3 3/4'	95,3 mm	18 1/4'	463,6 mm

4L80E 1991-Later (bellhousing pattern - Chevrolet)

Style	A		B		C		D		E
std. duty 2WD	32 11/16'	830,3 mm	26'	660,4 mm	30 3/8'	771,5 mm	4 1/4'	108 mm	20'	508 mm
heavy duty 2WD	31 15/16'	811,2 mm	26'	660,4 mm	30 3/8'	771,5 mm	4 1/4'	108 mm	20'	508 mm
heavy duty long	33'	838,2 mm	26'	660,4 mm	30 3/8'	771,5 mm	4 1/4'	108 mm	20'	508 mm
4WD	29'	736,6 mm	26'	660,4 mm	30 3/8'	771,5 mm	N/A	N/A	20'	508 mm

6L80E 2006-Later (w/ removable bellhousing)

Style	A		B		C		D		E
29 1/4'	742,95 mm	25 3/4'	654,05 mm

6L90E 2006-Later (w/ removable bellhousing)

Style	A		B		C		D		E
30 1/2'	774,7 mm	27 1/2'	698,5 mm

Splines (output shaft) Pan Bolts (number of)

Type	Output Splines	Pan Bolts
Alu. Powerglide (up to -63)	16 splines	14 pcs
Alu. Powerglide (from -64)	27 splines	14 pcs
TH350	27 splines	13 pcs
TH400	32 splines	13 pcs
TH200-4R	27 splines	16 pcs
TH700-R4, 4L60, 4L60E	27 splines	16 pcs
4L80E	32 splines	17 pcs
6L80E	31 splines	18 pcs
6L90E	36 splines	18 pcs

Chevrolet Transmission Service

Chevrolet Transmission Ratios

Chevrolet Transmission Identification

Transmission Ratios	1st to 2nd Ratio Drop	1st Gear	2nd Gear	3rd Gear	4th Gear OD
Turbo 350	1.00	2.52	1.52	1.00	N/A
Turbo 400	1.00	2.48	1.48	1.00	N/A
200-4R	1.17	2.74	1.57	1.00	0.67
700R4 / 4L60E with PATC close ratio gear set. Low geared 1st with 11,72% less 1st to 2nd RPM drop than the wide ratio gear set. This is the same ratio as a 4R70W transmission.	1.28	2.84	1.56	1.00	0.70
700R4	1.43	3.06	1.63	1.00	0.70
4L80E	1.00	2.48	1.48	1.00	0.75

Transmission Ratios	1st to 2nd Ratio Drop	1st Gear	2nd Gear	3rd Gear	4th Gear	5th Gear	6th Gear
6L80E / 6L90E	N/A	4.030	2.360	1.530	1.150	0.850	0.670

Transmission Fluid Capacity (see also capacity of fluid in the converter here)

Transmission (stock pan)	Number of Qts/L
Powerglide, TH350 (without converter)	4 qts / 3,8 L
TH400, TH200-4R, TH700-R4, 4L60, 4L60E (without converter)	6 qts / 5,7 L
4L80E (without converter)	7,7 qts / 7,3 L
6L80E Fluid capacity with 258 mm converter	10,3 qts / 9,7 L
6L80E Fluid capacity with 300 mm converter	12,6 qts / 11,9 L
6L90E Fluid capacity with 300 mm converter	13,8 qts / 13 L