I use an 8-3/4 in my 63 and so far have run 10.70's and it still has stock axles in it. Its an auto car that goes just over 3700 lbs and other then the Detroit Locker it is all stock. Now I only race my car 2 or 3 times a year at the most and usually just a test & tune where I only make a few passes. I did not race it at all this year because of some personal problems. But I want to go to a Dana and would have if I had the money when I built my 493. If you have the cash go with the Dana as its good insurance. And if you blow the 8-3/4 you will be pulling the trans to fix the overrunning clutch (sprag). I am pushing my luck everytime I race my 63 and I know it but I can not afford a Dana right now or I would have one. Ron