If you have your original brake hoses on your car you might want to change them out first and see if your calipers are the problem. When the hoses get old the fluid does not return when you let up on the brake so your brakes can drag and wear out prematurely.
If that doesn't work Phil has rebuilt calipers which do not cost an arm and a leg. It might be a good way for you to go.

__________________
Tom Hughes
St. Louis
84 300SD
92 300D
86 300SDL