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Tech/Performance/Info >> Transmission and Differential Questions and Solutions >> 1971 L48 Rear Differential
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Message started by Richard on Oct 31st, 2015 at 10:47am

Title: 1971 L48 Rear Differential
Post by Richard on Oct 31st, 2015 at 10:47am
Hello knowledgeable folks,

I’m working on my 1971 base model L48 coupe built in January 1971 (F16 on door plate).
It has matching engine numbers, looks to be the original 71-CK THM400 tranny but the rear differential looks to be a 1978 with ID “OKO37W8E1”. If I was to find a 1971 differential housing, I gather I would look for an “AW” (3.08) (L48) but what other numbers/letters would I look for so that it would appear to be build prior to January 1971 as per the VIN to become a matching numbers car again? or is that even possible?

Thank you,
Richard

Title: Re: 1971 L48 Rear Differential
Post by Artsvettes on Nov 1st, 2015 at 1:49pm
You would be looking for the date code that would be casted into the housing at the foundry. Finding with your build date will be a chore to say the least. Not saying it is impossible though...................jack

Title: Re: 1971 L48 Rear Differential
Post by Richard on Nov 1st, 2015 at 6:17pm
Thanks Jack.
Even if I had a housing that was built prior to the vehicle date (January 71) would probably be fine but I haven't found the code breakdown for 1971 and newer differentials. There seems to be a lot of info on the older housing code sequences but not on the 1970 or 1971 and newer. Does anyone know how to get the date and other info from the later C3 housing codes?
Cheers,
Richard

Title: Re: 1971 L48 Rear Differential
Post by Artsvettes on Nov 2nd, 2015 at 8:56am
Saw this one on ebay item number 161871264002 it is from a 71 big block AW I didn't see the date code............jack

Title: Re: 1971 L48 Rear Differential
Post by Richard on Nov 2nd, 2015 at 10:33am
I saw that one. It is definitely LT1 or big block etc. because of the u-joint straps and threaded bolts rather than U-bolts on the stub shafts.
I can't seem to find any info anywhere on deciphering this years differential codes? Its weird.

Cheers,
Richard

Title: Re: 1971 L48 Rear Differential
Post by 69Shark on Nov 6th, 2015 at 6:39am
Hello,
I'm absolutely NOT an expert here but maybe have an idea?
Have you considered looking at info for earlier/later cars since you can not find specifics on the 71. For example I have a 69 and know there are restoration books that go into pains taking detail of every mark, sticker, label, tag, part, piece, and factory correct writing from workers on the car.

Maybe finding one of these books for a 69 could give you insight as to what the 71 might be labeled like. 

Again, I am no expert and am only interested in the appearance of a stock 69 so that is as far as my number knowledge goes!

Good luck!
Scott

Title: Re: 1971 L48 Rear Differential
Post by Richard on Nov 8th, 2015 at 5:40pm
Hey Scott,
I bought an AIM and its awesome but I haven't shelled out for a restoration book yet. There is so much info here and on the interweb that I haven't had to buy a resto book yet.
The 70 and older codes seems to be deciphered but the 71 and up C3s diffs seem to be different and illusive.
I will find out and post it when I do...
cheers,
Richard

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