This company is referenced quite often as a good and reliable source.
http://www.tomsdifferentials.com/
You might try a local Corvette club though and see what info you can get there. The 36's are frequently changed out by owners for 44's as I have done when folks put more power to there A4's. You can often oick up whole rear ends in good condition from $200 - $400 depending on the gearing and condition. Lot's of 2:59's out there and 3:07's come up every so often.
If you put in the whole batwing and pumpkin, it's really an easy job to do if you're any kind of wrench at all. Good luck and welcome to CAC
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LOW 12'S, 11'S ARE IN THERE



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