Hi Jeff,
I received your e-mail on my address, sorry, I'm new to this, but I'm learning.
Regarding the rubber support on the rear coil spring of my sl, are worn out (lower). Sometimes I would hear a noise(metallic) when I make turns, not all the time. You said, more important are the top rubber cushion.
What are progressive springs?
Hope you don't mind me asking your help or question, now that I know that there's someone to ask.
Yes I have Haynes manual and another EURO book.
Thanks. Dan