1969 El Camino Rear Axle Identification
The rear axle identification code consists of a two 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: CG1025B decodes to CG ~ 3.36 Positraction, 1025 ~ Month [Oct] and Day [25], B ~ Buffalo (G=Chevrolet Gear & Axle, W=Warren, K=McKinnon Industries)
Casting Numbers:
12-Bolt Casting #3917124 (early model year), #3959038NF
(late model year)
10-Bolt Casting #3859037NF
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.
| Prefix | Axle Ratio |
| CA | 3.08 ~ 10-bolt (L14/307)* |
| CB | 3.36 ~ 10-bolt |
| CC | 3.73 ~ 12-bolt |
| CD | 3.07 ~ 12-bolt Positraction |
| CE | 3.08 ~ 10-bolt Positraction |
| CF | 3.31 ~ 12-bolt Positraction (L34/396)* |
| CG | 3.36 ~ 10-bolt Positraction |
| CH | 2.73 ~ Positraction |
| CI | 3.73 ~ 12-bolt Positraction (L34/396 & L78/396)* |
| CJ | 2.56 |
| CK | 2.56 ~ Positraction |
| CL | 2.56 ~ 10-bolt (L65/350-2)* |
| CM | 2.56 ~ Positraction |
| CN | 2.56 ~ 12-bolt (L48/350-4)* |
| CO | 2.56 ~ Positraction |
| CP | 2.73 ~ 10-bolt (L14/307)* |
| CQ | 2.56 ~ 10-bolt (L65/350-2)* |
| CS | 2.56 ~ Positraction |
| CT | 2.73 |
| CW | 3.31 (L35/396, L34/396 & L48/350-4)* |
| CX | 3.07 ~ 10-bolt (L35/396)* |
| CY | 3.07 ~ 10-bolt |
| CZ | 2.73 |
| KA | 3.55 small ring gear |
| KB | 2.56 ~ Positraction, small ring gear |
| KC | 2.73 ~ Positraction, small ring gear |
| KD | 2.73 ~ 12-bolt large ring gear (L48/350)* |
| KE | 2.73 ~ Positraction, small ring gear |
| KF | 3.55 ~ 12-bolt Positraction, large ring gear (L35/396 & L34/396)* |
| KG | 3.08 ~ 12-bolt small ring gear |
| KH | 3.08 ~ 12-bolt Positraction, small ring gear |
| KI | 3.36 ~ 10-bolt |
| KJ | 3.55 large ring gear |
| KK | 4.10 ~ 12-boltPositraction (L78/396)* |
| KL | 3.36 ~ Positraction, small ring gear |
| KM | 4.56 ~ 12-bolt Positraction |
| KN | 3.55 small ring gear |
| KO | 4.88 ~ 12-boltPositraction |
| KP | 3.55 ~ Positraction, small ring gear |
| KQ | 4.10 ~ 12-bolt Positraction, heavy duty (COPO)* |
| KX | 3.07 ~ 10-bolt ~ Positraction |
| FH | 2.73 |
| FI | 2.73 ~ Positraction |
| FJ | 3.08 ~ 12-bolt |
| FK | 3.08 ~ 12-bolt Positraction |
| FL | 3.36 ~ 10-bolt |
| FM | 3.36 ~ 10-bolt Positraction |
| FN | 3.55 |
| FO | 3.55 ~ Positraction |
| Assembly Month - 1st and 2nd numbers | |||
| Number | Month | Number | Month |
| 01 | January | 02 | February |
| 03 | March | 04 | April |
| 05 | May | 06 | June |
| 07 | July | 08 | August |
| 09 | September | 10 | October |
| 11 | November | 12 | December |
Assembly Day - 3rd and 4th numbers
01...31
|
Rear Axle Assembly Plant - 5th letter |
|
| Code | Assembly Plant |
| B | Buffalo, NY |
| G | Chevrolet Gear & Axle |
| W | Warren, MI |
| K | McKinnon Industries |
* Engine RPO code and size following the rear axle ratio are taken from build sheets or protect-o-plate warranty cards and may not reflect the only engine the rear axle codes came with. Where there are no RPO/engine information following the rear axle code only means I do not have documentation to verify them.
