Miscellaneous Codes
Rear Axle Codes
The rear axle identification code consists of a three letter prefix indicating the gear ratio, four digits indicating the assembly date as month/day, and a single letter suffix indicating the manufacturing location. The identification code should be stamped on the bottom or font of right axle tube either adjacent to the carrier housing or about 8" - 10" inboard from the backing plates. The particular engine RPO code is listed in parentheses as found on build sheets.
Example: CGI0629B decodes to CGI ~ 3.36:1 Positraction, 0629 ~ Month [June] and Day [29], B ~ Buffalo (G=Chevrolet Gear & Axle, W=Warren, K=McKinnon Industries). If a "1" or "2" exists, it indicates the plant shift number. See bottom of page for photo examples.
Casting Numbers:
12-Bolt Casting #3969278
10-Bolt Casting #3969277
The casting numbers/letters on rear end housings may have either a prefix or suffix of "N" or "NF" and no reason has been found yet why they may have one or the other. Codes below are for Chevelle & Monte Carlo.
| Prefix | Axle Ratio |
| CCA | 3.08:1 ~ 10-bolt (L14/307 & L22/250)* |
| CCB | 3.36:1 ~ 10-bolt |
| CCD | 3.07:1 ~ 12-bolt Positraction |
| CCE | 3.08:1 ~ 10-bolt Positraction |
| CCF | 3.31:1 ~ 12-bolt Positraction (L34/402)* |
| CCG | 3.36:1 ~ 10-bolt Positraction |
| CCH | 2.73:1 ~ 12-bolt Positraction (L48/350-4)* |
| CCL | 2.56:1 |
| CCM | 2.56:1 ~ Positraction |
| CCN | 2.56:1 |
| CCO | 2.56:1 ~ Positraction |
| CCP | 2.73:1 ~ 10-bolt (L14/307)* |
| CCW | 3.31:1 ~ 12-bolt (L34/402 & LS3/402 M.C.)* |
| CCX | 3.07:1 ~ 12-bolt |
| CGA | 2.56:1 ~ 10-bolt (L65/350-2)* |
| CGB | 2.56:1 ~ 10-bolt Heavy Duty Positraction (L65/350-2)* |
| CGC | 2.73:1 ~ Heavy Duty |
| CGD | 2.73:1 ~ Heavy Duty Positraction |
| CGE | 3.08:1 ~ 10-bolt Heavy Duty |
| CGF | 3.08:1 ~ 10-bolt Heavy Duty Positraction |
| CGG | 3.36:1 ~ 10-bolt Heavy Duty |
| CGI | 3.36:1 ~ 10-bolt Heavy Duty Positraction |
| CKC | 2.73:1 ~ Positraction |
| CKD | 2.73:1 ~ 12-bolt (L48/350-4 & LS3/402)* |
| CKF | 3.55:1 ~ 12-bolt Positraction (L78)* |
| CKJ | 3.55:1 ~ 12-bolt (L78/402)* |
| CKK | 4.10:1 ~ 12-bolt Positraction |
| CRJ | 2.56:1 |
| CRK | 2.56:1 ~ 12-bolt Positraction (LS5/454)* |
| CRL | 3.07:1 ~ 12-bolt |
| CRM | 3.07:1 ~ 12-bolt |
| CRU | 3.31:1 ~ 12-bolt (LS5/454)* |
| CRV | 3.31:1 ~ 12-bolt Positraction (LS5/454 & LS6/454)* |
| CRW | 4.10:1 ~ 12-bolt Heavy Duty (LS6/454)* |
