1966 Rear Axles
All '66 Corvette rear axles are stamped with an alpha-numeric identification code. The 7-digit code contains the axle code prefix, the month and day build code, an axle plant letter suffix code, and, on positraction axles, a letter code stamped below the axle code to provide source information.
On the '66 Corvette IRS rear suspension, the differential code is stamped on the bottom of the differential carrier housing just forward of the rearend cover. The axle code reads from left to right. The two-letter prefix designates the gear ratio and any other specific information about the axle. The calendar month is designated by a two number code from January (01) through December (12).
 It's hard to believe that...  It's hard to believe that this stout little 327 has seen more miles than some diesel trucks. With more than a quarter-million miles on the odometer, Freddy had the small-block freshened up in 1994 just to ensure a few more years' survival. |  |  In 1991, Freddy took this...  In 1991, Freddy took this photo at the Aquasco Speedway (Aquasco, Maryland) that closed about 1974. Anyone out there remember racing a Corvette at this track? |
Plant Code
W = Warren, MI
| Positraction Code |
| Example: AL-04 09 W E |
| AL = | Axle Prefix: 3.08:1 for a 327 Corvette positraction axle |
| 04 = | Month: April |
| 09 = | Day: 9th day |
| W = | Assembly Plant: Warren |
| E = | Positraction Source: Eaton |
| 1966 Rear Axle Codes |
| Engine | Gear Ratio | Code |
| 327 | Std. Ratio 3.36:1 | AK |
| | Posi 3.08:1 | AL |
| | Posi 3.36:1 | AM |
| | Posi 3.55:1 | AN |
| | Posi 3.70:1 | AO |
| | Posi 4.11:1 | AP |
| | Posi 4.56:1 | AQ |
| | 3.08:1 | AR |
| | 3.70:1 | AS |
| 427 | Posi 3.08:1 | AT |
| | Posi 3.36:1 | AU |
| | Posi 3.55:1 | AZ |
| | Posi 3.70:1 | FA |
| | Posi 4.11:1 | FB |
| | Posi 4.56:1 | FC |