No matter how you look at it you have to weigh out how the car will be used to see if it will hold up. Sure a street car that does not see a sticky tire it will be fine. But a car thats raced with slicks or drag radials there is a good chance something in the 8-3/4 may break sooner or later. I really want to upgrade to a Dana in my 63 but my funds are very limited right now. But the price Dr Diff has a Dana for makes me want to borrow the money and go for it. Believe it or not the 8-3/4 in my 63 is all stock other then the Detroit Locker I put in it and the 4.30 gears. I know I am running on borrowed time but I dont race my car much as I mostly drive it on the street and I dont street race. In fact I have only put 4 passes on my car in the last 2 years. Funny as back in the 80's I bracket raced a 66 Dart with a 340 and 4-speed. It had an 8-3/4 from a 68 Dart in it and I broke that rear at least 4 times between ring and pinions and carriers. I finnally went to a spool and then broke driveshafts and U-joints. It was basically a stock 833 but I launched it hard as when I let the clutch out the go pedal went to the floor all the time. It ran a best ever of 11.94 at 113 and my 63 with a stock 8-3/4 has not broke anything yet and of course its much faster and heavier but it is an auto. I have raced my 63 about 10 times since 2006 and it ran mid 11's until 2011. I have raced it 4 times with the 10 second eng in it. I dont plan to race again until I beef it up or go to a Dana. If the 8-3/4 breaks I will be going thru my trans also. Ron