Well I took care of the muffler rattle. For now at least. I used an old stethoscope to figure out exactly where the rattle was coming from. Then I gently adjusted the outside of the offending muffler with a pry bar. $0.
Got these in the mail yesterday. Should put the truck dead level when unloaded. As an added bonus, they'll use up most of the excess threads on the U-bolts.
Probably be a couple weeks before they go in though. I'm tired of disassembling the rear on this truck.