I live in Tucson, and drove my 85 300 TD to LA last week. While there, I developed a clicking noise that happened only under load and was rpm sensitive.
I went to a couple of indies and was not impressed. Ended up going to a dealer out of desparation. Walters MB, and in particular Darryl Wheeler, their Classic Car Team Leader, did a spectacular job.
He ID'd the problem as a bad tranny linkage bushing. He not only fixed it for less than a C note, but while he was at it readjusted the tranny (shifts like new), tightened up the steering, and replaced a leaking fuel line.
I can't recommend they guys strongly enough!