I put the car up on the alignment rack at work and the rear alignment was pretty straight. Very slight difference between right and left.Not enough to be in the red anyway but it wouldn't take much to make the axles bind up in the splines. I recently installed a PowerLock unit with brand new upgraded spider gears and it was even worse with brand new splines.
There is a rear end shop about 40 minutes away that can straighten my housing and re-tube it with chrome molly tubes if necessary.
This is the deal that the Mustang guys are running
Gus