Steve. I wouldn't use anything solid there unless the car is only ever driven moderately in a straight line. The leaf springs act as both the lateral and horizontal locator for the axle. When the car pitches into a corner, the leafs must be able to camber side to side to allow the axle to arc as needed. In that regard the leafs being tied together by the axle also act as a pseudo anti-roll bar, with the rate being determined by the amount of "give" that the isolation pads provide. Adding solid pads would be like adding a rigid sway bar to the rear. It could be dangerous for a street car and it may add quite a bit of NVH as well. I would go with a good rubber, or poly pad.

Hello again Jason, in some of the responses you've posted to my previous questions, I get the sense you've been through some of this before. I'm replacing the BOP rear with a 9" ford that has GM original style perches. I'm planning to reuse my original springs for the time being. When I transferred the leafs over, the rubber isolation pads (top and bottom) looked pretty beat up. I've read that some people have replaced these with metal spacers for higher horsepower applications. I've made a couple calls to Calvert and Currie and they're both unfamiliar with any metal replacements. My car and rear(s) are both set up for factory multi-leaf. Have you encountered this before? Would you just recommend going with something like a poly urethane type pad? Thanks very much for the thoughts and advice.

-steve