I think Bill's on to something here... Delrin would absorb just a little shock without deforming as much as a poly bushing. It's probably a better idea, seeing as how we're not supposed to be reinforcing the suspension mounting points in IT (except where the cage mountings coincide, I know, I know!).

Production is the place you find a lot of this, maybe they'll be a better source for you in this regard.

-Tom