[Jeff Lee]

The secret to long life on an 8.75 is use billet caps and spanner adjuster. They're available from Mark Williams. Summer Brothers used to make them but I'm sure they're very difficult to locate. I think if you use all MW products in that rear you'll be much happier even though more money will be spent. My buddy Mark with his C/S '70 440-4 Challenger has a complete MW 8 3/4 rear with 4.88's. Launching with too much clutch pressure @ 6K has yet to show ANY abnormal wear.
I agree w/ 340 'Cuda, if it were a Dana 60 good used would be OK. I've done it myself. In fact the 4.88's I ran were previously in an A/S Max-Wedge car for 500+ runs and then in mine for a few hundred. Nobody knows how many runs they have seen but they still look perfect. I don't think I would try that for your rear though. Good luck!