I love my poly body mount bushings. Compared to the shredded and missing stock bushings, no comparison. If your stock rubber bushings are in good shape, keep them. How to tell if they are in good shape? Look at them, 10 sets in all, top and bottom bushing half. If they are deeply cracked and hardened or deteriorated and mushy (able to squeeze them with your fingers), then they are due for replacement.

On my '85, 2 of the 10 bushings were nearly shredded due to PO installing a bumper wrong, and one bushing was gone, no trace of it, again I suspect the PO was to blame. Likely the mounting bolt had the nut come loose and fall off. leading to a rattling noise from the loose bolt. PO, in a moment of insight, finds loose bolt and concludes that this is the cause of the rattle and pulls it out, problem fixed as far as he is concerned! The remaining 7 bushings were deeply cracked on the outside and the remaining rubber was about the consistency of silly putty.