Most of my body mounts rubber bushings are crumbling. Currently doing the LS and Vintage Air so the front 2 are easy to get to now. Looking around and the various kits and trying to figure out the differences. Some of them depending on vendor are just the rubber bumpers, bushings, and washers. $60 or so. The other kits are more complete with shims and bolts $160. $100 for bolts and shims seems a little high to me since I can buy grade 8 bolts for $5 a pound. What am I missing?