68' Dart

Your question and my response is gonna open up a can of worms that would probably be better addressed in a different forum. But simply put, and this is strickly my opinon,(opinons are like a--holes, everybody's got one) the 9" is a stouter rear end than the 8.75". Don't get me wrong, I've had some very reliable 8.75's, but there was a reason Mopar didn't install them behind the Hemi's. I broke one at the track years ago and ruined a good pair of drawers. The Dana 60 is the ultimate set-up, but have you ever tryed to change gears on a Dana at the track? I can take 2 or 3 9" punkins with me and have one changed before I can get the differential out of a Dana. Good 8.75's are getting harder to find and the ones I have i'm saving for the hard-core Mopar restorer's. Another reason is, I've probably got a dozen 9" punkins with vairous gears, splines, locker, open and spools laying around. For me it was a no brainer. $$$$