I have a new to me 1975 w115 300D that I will be bringing to a local independent MB shop for a good look over today. What are some things that should be inspected for this vehicle? It has 120,000 miles. I don't have great service records for it but it seems the previous two owners kept it in generally good condition. I am pretty green when it comes to cars and especially diesels. At the least I will get the oil changed as well as the fuel filters changed. Some known issues:

Transmission hesitates or won't shift from 1st to 2nd without letting off the gas.
Oil leaking from behind the cluster (I think) in to the driver foot well.

Fluid leaks which I dont think are oil as it is not black, possible power steering, transmission or brake fluid or a combination of those.

Any help or suggestions are appreciated.