BB72

I thought I would share some info with you guys since I'm going through it right now. Differential identification always seems to be a difficult one. For starters, the location of the ident. numbers are on the bottom of the diff on the flat spot between where the spring bolts to and the rear diff cover. Sorry about the condition of the arrow.



Ok, here's and example of how to read the numbers.Lets say the stamp reads OH C2181 . OH is the axle code or prefix, the C is the assembly plant, the 218 is the day of the year and the 1 is the shift. The OH represents a 78-79 3:55 ratio diff.
Other axle prefixes or codes are as follows, I'm sure this site will cover most. It's very informative.It takes any mystery out of decoding.

http://www.corvette-world.com/corvet...tification.php

Rob

avner

On my 68 (G14 – Feb/14/68) diff' the stamp read 2AP 2 5 68 W, so the decoding look deferent.
2 =?
AP = 4.11
2 = ? =>Feb
5 = ? => Day# 5
68 = 68
W = Warren Manufacture

Avner

BB72

I'm sure date codes change a bit. I have one thats 8E1, I know it's a 78 for sure.

1973bluevettee

My differential code in the spot you said to look is AW W341 E1. Any help here what’s my ratio and is it a posi or open dif???

Bikespace

Here's another website to try:

http://corvettec3.ca/axle.htm

AW is 3.08 in all the years that code was used (68 through 75, including 73). All C3 diffs were posi from 71-82, but it was possible to have an open diff before that. I don't know how to decode your diff's birthday, though.

69L88

W341 indicates built at the Warren (MI) plant on the 341st day of (presumably) 1972 which would be Wednesday, December 6. I say presumably because I don’t know if the differential is original to your car. Look on the left side of the casting for a raised date code like in the example below. What’s the last 5 of your VIN?

The E indicates an Eaton posi unit was installed and the 1 indicates the differential was built on the 1st shift.