Rear End Code Decipher Help

[Larry E.]

Can someone try to decipher the code on the picture given. Code does not
match up with the new 66 TIM & JG manual. Thanks in advance.
Larry

[John H.]

Re: Rear End Code Decipher Help

Can someone try to decipher the code on the picture given. Code does not
match up with the new 66 TIM & JG manual. Thanks in advance.
Larry

Larry -

"FC" was a 4.56 Posi Big-Block axle from '65-'69, but I don't think Julian dates were used until 1971; what's the diff housing casting date (driver's side, partially obscured by the strut rod bracket)?

[Kenneth T.]

Re: Rear End Code Decipher Help

I have posted a picture of the codes for several years. The last line for '66 shows an FC code.

Hope it helps.

Ken

[Larry E.]

Re: Rear End Code Decipher Help

Larry -

"FC" was a 4.56 Posi Big-Block axle from '65-'69, but I don't think Julian dates were used until 1971; what's the diff housing casting date (driver's side, partially obscured by the strut rod bracket)?

John:
Can not get to car right now to look at casting date as it is sealed in a "OMNI"
bag right now. Don't know when I will "unbag it".

Larry

[Larry E.]

Re: Rear End Code Decipher Help

OK we know the FC is 4:56 ratio HD Posi and "W" is for the Warren MI Plant. Has anybody ever seen a 65-69 coded Rear Axle with a Julian
Date instead of the normal M-DD-YY Date? Any pictures out there?
Thanks in advance. Larry

[Terry M.]

Re: Rear End Code Decipher Help

Larry, as you know we don't routinely judge differential codes, but I have never heard of a 1968 to 1970 with an originally installed Julian dated differential. I would have to do some research to find out if the Julian date system began in late 1970 production or if the standard system carried over into early 1971, but that is a long way from your Corvette.

[Larry E.]

Re: Rear End Code Decipher Help

Moved this up once more for final time. Can anybody post a picture of a Julian dated 1971 or up for comparison? Thanks; Larry

[Larry M.]

Re: Rear End Code Decipher Help

Moved this up once more for final time. Can anybody post a picture of a Julian dated 1971 or up for comparison? Thanks; Larry

Larry:

No pictures..........sorry. I suspect this to be a later GM over-the-counter replacement. Previous owner may of had extra $$ to buy new GM parts or worked for a GM dealership. That's why codes and other markings are factory correct, but with a later date.

Larry