Yes indeed, you will have to grind the perches to fit the axle. The perches will have to be at the same plane as the springs or the ubolts will not fit. I just ground a little off of each side and they fit pretty good. I bolted everything up under the truck just where I wanted it (with all the weight on it) and welded the perches on. i don't see any other way to get it right. This will enable you to get the pinion angle correct. Good Luck with it.
