What about the front and back

I will help a couple friends with their early 80-'s diesels. This morning I installed a right rear window glass, changed the oil/filter and replaced some of the diesel fuel return hoses on a 300SD for $60. I had one guy ask me about replacing rotors/pads on a 1991 Volvo. I told him $120+parts and have not heard back from him. I really don't have a desire to work on anything except the early 80's diesels. I have to enjoy it.