What would be the easiest way to change body mount bushings and shims on a impala with body in place? My idea is loosen up all body mount bolts and then start at the rear by placing 2 jack stands on the frame and lifting the body easily with the floor jack and a 2x4 or would this be to risky on the floor/trunk metal? Also what's the correct size thickness of body shims? I was looking up the shims and they're expensive, if I can id rather go to the local hardware store and pick up some squared galvanized washers. Car is a 1963 impala 2 dr hardtop