Timing chain: 1981 300 D

While driving on the highway, my 1981 300 D suddenly lost power and the engine died. It makes a loud squeal and seems to stop short when I try to start it. The loud squeal comes from the top of the engine at the front, and I strongly suspect timing chain problems.

Just wondered if anyone has experience with this sort of thing and can comment. Although I haven't disassembled anything, it sounds like I may be in real trouble here. Is there any way of checking the lower pullies, tensioners, etc. without pulling and disassembling the engine? The Haynes manual makes replacement of the chain sound like a two man job, and that means the shop as I have nobody here to help with it.

If so, does anyone know of a good shop that does diesels (other than dealer) in the Cincinnati vicinity?