I just took a rear spring off - holy @#$%. According to the TCI info, the rears are 300/540 progressive rate springs (effective rate 282/508 @ .94 for the 13* installed angle). No wonder the car wallowed with effective 150 in lb on the front and these on the rear - plus there was NO give to it at all. The worst part - these springs are 11 inches long, not the normal 10's, so I need to do a web search for a supplier other then s-l-o-o-o-w TCI.