1973 El Camino Rear Axle Identification
The rear axle identification code consists of at least a two letter prefix indicating the gear ratio, a letter for the GM Division, and three digits indicating the day of the year from January 1. 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: CDC0642E1 decodes to CD ~ 3.08:1 Positraction, C ~ Buffalo, 064 ~ day of year starting with January 1 (the 64th day being March 5), 1 or 2 ~ shift (if present), E ~ Eaton Positraction
Casting Numbers:
12-Bolt Casting #(unknown)
10-Bolt Casting #(unknown)
| Prefix | Axle Ratio |
| AC | 2.73:1 |
| AD | 3.08:1 |
| AJ | 3.42:1 |
| CC | 2.73:1 Positraction |
| CD | 3.08:1 Positraction |
| CJ | 3.42:1 Positraction |
| WA | 2.73:1 |
| WC | 3.08:1 |
| WE | 3.42:1 |
| XB | 2.73:1 Positraction |
| XC | 3,08:1 Positraction |
| XE | 3.42:1 Positraction |
Assembly Day - Day of the year, 000...365
Shift - 1 or 2 (or Day / Night)
|
Rear Axle Assembly Plant - last character |
|
| Code | Assembly Plant |
| C | Buffalo, N.Y. |
| G | Detroit Gear & Axle |
| K | McKinnon Industries (GM of Canada) |
| W | Warren, MI. |
