1965 Chevelle Rear Axle & Differential Identification

Picture of a rear differential

Casting Numbers

These are the casting numbers used during this production year. If they were used during another year, you will find the additional years listed below.

10 Bolt Housings
Casting Year
3959139N 1965
12 Bolt Housings
Casting Year
3859140N 1965

Decoding Rear Axle Codes

The rear axle identification code is stamped on the axle housing on the bottom, front left, or front right axle tube next to the carrier housing or about 8 to 12 inches from the backing plates. This code consists of 7 digits and characters indicating the stock gear ratio, month/day of assembly, and the assembly plant. Sometimes you will find an extra character stamped near this code, E indicates Eaton positraction.

For example: CF0312B decodes this way: CF / 03 / 12 / B.

Code Gear Ratio Notes
CA 3.08  
CB 3.36  
CC 3.73  
CD 3.07 Positraction
CE 3.08 Positraction
CF 3.31 Positraction
CG 3.36 Positraction
CH 3.70 Positraction w/ Metallic Brakes
CI 3.73 Positraction
CJ 3.07 Metallic Brakes
CK 3.07 Positraction w/ Metallic Brakes
CL 3.08 Metallic Brakes
CM 3.08 Positraction w/ Metallic Brakes
CN 3.31 Metallic Brakes
CO 3.31 Positraction w/ Metallic Brakes
CP 3.36 Metallic Brakes
CQ 3.36 Positraction w/ Metallic Brakes
CR 3.70 Positraction
CS 3.70 Positraction w/ Metallic Brakes
CT 3.73 Metallic Brakes
CU 3.73 Positraction w/ Metallic Brakes
CV 3.70 Overdrive
CW 3.31 "327" w/ Air Conditioning
CX 3.07 "327"
GA 3.31 Heavy Duty
GB 2.73 "327" w/ Powerglide
GC 2.73 Positraction
GD 2.73 Metallic Brakes
GE 2.73 Positraction w/ Metallic Brakes
Code Assembly Plant
B Buffalo, NY
G Chevrolet Gear & Axle
W Warren, MI
K McKinnon Industries