In a 2001 Ram 2500 with 120,000 miles I started hearing a heavy clanking noise when braking, you could hear it on the right hand side of the truck. Took it to a supposedly professional brake shop, mechanic said it was the front right wheel, lifted it up, and...nothing, everything looked fine on that wheel. He told me to go to a suspension specialist, may be some bushing was loose.
The suspension specialist found that the rear right wheel brake system had some loose parts, coiled springs were missing, found a half circle sheetmetal part inside the drum. Parts got chenged and everything has worked fine since. I guess watch out for a lazy mechanic.