I'm looking to buy a car and I've found two inexpensive 1976 Mercs. One is a 450SE and the other is a 240D. Can somebody provide some info about maintenance costs and reliability?

I'm good at tinkering with things and fixing mechanical problems within reason. Are these the kind of cars you can do basic repairs by yourself? Is one particular engine more reliable than the other? They both appear to be in good condition from the pictures I've seen so far.

I've heard mechanical parts are common enough that they are easy to find and get fixed but interior/exterior body parts are tough and expensive. True?