You went from the Plymouth to a very obscure Volvo! I think I've worked on 2 diesel 240 Volvos, and I believe both of them were Autos. Sometimes with the older Euro cars, having a stick in the older diesel equipped vehicles was a lesson in smooth clutching and shifting to keep the vehicle moving smoothly during traffic. While you may have had a clutch issue with oil from a leaking seal, sometimes it was the nature of the beast and nothing was wrong. I still remember getting used to driving older Mercedes-Benz 240D models with a stick, not easy to get a silky smooth shift since you ran out of RPMs so fast with the diesels and had to shift up in a hurry. I much preferred the larger M-Bs with an auto if a diesel was going to be in front of the trans, esp the more powerful versions. 'Them's were the days'.....