325i Rear End Rebuild

My buddy and I am a bout to embark on rebuilding the rear end on our 1992 325i. The car will be used for Track purposes only. We will be upgrading to the M3 rear sway bar and brakes. We are tossing around the idea of using poly bushings, but they are expensive. Is there any location where polyurethane bushings are a "must have"?



Thanks is advance for you advice.

325i Rear End Rebuild