I own a 1990 Formula with the WS6 suspension. I did a search for this but nobody is really describing a noise like this that I could find. My car makes a 'Heavy' metal-on-metal crunching sound when you go over something like speed-bumps or train-tracks. I have already installed the complete Energy Suspension bushing kit. I have new Monroe shocks. I've double checked all of bolts. I've even torqued everything according to the GM service manual. I've downloaded the GM bulletins concerning rear-end noises. They recommended inverting the emergency-brake cable retainer, and turning the coil-springs where the 'tails' were pointed towards the front of the car. I did both of these things and it didn't make a difference. The only thing that I can think of that I haven't done is replaced the factory coil-spring isolators. I've ordered two different sets from Energy Suspension but neither of them fit. Does anyone know the correct part number for the isolators? Does anyone have any other suggestions? Thank you for any help.