Just ran into this problem two days ago.
91 Woody is correct, I just put on 4.5", I lenghtend the stock arms so i could mock up the lift for axle fab, and found that you cannot rotate the axle back far enough to hook up UCA's, the lower arms hit the coil brackets... So grab some tubing bend up some arms and that worked.
Now if oyu compressed the springs ,that would make a difference.