[sprint_9]

Mine is at 6 degrees down. Im using squarebody clamshells retrofitted into a 72 frame, so more or less the same design I think.

I agree with Mongo, check your pinion angle before you change anything else. You might be right where you need to be, or closer to what you need. My pinion started at 9 degrees up, I shimmed it 4 degrees down to get it to 5 degrees up. This got both angles within about 1 degree which is what you want. It also makes a difference on your angle split if you are running trailing arms or leaf springs. Trailing arms you should have 1-2 degrees down on the pinion when compared to the transmission output shaft, leafs are more, not sure on the number though.