what i was trying to point out in reply # 21 -- is the pinion offset --- yes they are being used in A-bodies but your driveshaft is not running true to the stock factory location --
That may be true if your putting it under there without cutting down the long tube to center it up. However when you cut down the long tube and center it up the pinion will run in about the same place that an 8.75 pinion will be, give or take maybe 1/4". This amount wont be enough to wipe out u joints in short order.
An 8.75 pinion as well as all the rest of them is offset to the right of center as well. People put more loading on a u joint than that possible 1/4" deviation by jacking up or lowering the *** end.