The quality of replacement parts today is the major road block to keeping these old vehicles reliable and on the road these days.

As an example I rebuilt the front end on my 92 D250 about three years ago using all Moog parts. The outer tie rod boots wouldn't last a month and the upper control arm bushings were shot after two years. The truck still had all the original pieces from new when I rebuilt it that lasted over twenty years and 200,000 miles. There is some pretty crappy stuff being pedaled out there today and it isn't all made in China stuff either. I've had made in the USA stuff be just as bad or worse.