Rear suspension pinging noise

[Alan Hamm]

'87 300SDL - 230K miles

Several months ago I had a disturbing pinging noise that occurred when I went over speed bumps. Made a very pronounced "twang/pop" Really was a cross between a spring noise and someone tossing a golf ball inside the trunk.

Had it checked out and a rear shock was leaking, plus a lower control arm had a rust hole in it (not bad). Replaced the shocks around Christmas and it went away. Until about 2 weeks ago. Started coming back. First over speed bumps, then not so consistantly. But it might do it 2 or 3 seconds after a bump. And of course, not every time.

Concerned, I took it to my Indy today who heard it a little (of course it was not consistant when I needed it to be). We put on a lift and did not see anything earthshattering. To me, it sounds like a broken spring, but there was no evidence of that. There were some small boots inside the rear wheels that were cracked and open and they recommended replacing these, but indicated it was not critical.

So not sure what it is. Anyone have a similar noise and fix it?