Scotty did you ever find out what this was because I have exactly the same thing on my W124. I just replaced the tierods and draglink so I know its not those. In fact it seems like replacing those has made it more audible.
Its a sometimes rapid fire low faint thumping and it only happens on bumps any bumps. You sometimes need a series of small bumps to actually distinguish it.
Let me know Thanks!

yal
88 230E(W124)

[This message has been edited by yal (edited 08-25-2000).]