From the main SE-R mailing list...FYI
Lucky bastards! Now if only we can find something for the front!I found out this weekend that the resr suspension bushings (and bushings only) are interchangeable between the P10 and the B13. The arms themselves are similar, but different lengths, so you cannot swap those. But the actual bushings themselves are identical. This means you can buy the rear B13 Energy Suspension kit and install it on a P10.
So, just in case anybody wanted to know, now you know.