Body allignment question...

[72gmcshorty]

I'm soon going to be getting the body work done on my 2wd blazer. It's going to need floors, rockers, supports, etc. Should I replace the rubber body mount bushings before this work gets done or after? My driver side has a considerable sag to it. (There is quite a large gap between the door and the fender and a normal sized gap between the door and rear body panel. I think it's because of sag.) Is there a difference between blazer bushings and pickup bushings? Does anyone know what the total distance is suppposed to be between the frame and the support? (Bushing plus shim?) And finally, anyone have a part number for the poly bushings for 2wd blazer? Thnaks.