OK - I replaced the traction rod bushings in the rear with poly - new rubber in the rest. The rear trailing arm bushings went 25,000 miles and then failed completely. Just replaced all rubber with poly in the rear.

Put all poly in the front, with the exception of the lower stabilizer link bushings - the ones that attach to the control arm - and they lasted three days before failing.

Seems any poly tightens the joint so much impacts and vibration go to the remaining rubber - and hammer it to a premature death.

Make sense?

Now, the entire suspension - every bushing that is! - is poly and the ride is great!