BearClaw
FRF Addict
A lot of options and solutions already, but I will add my own experience with 'squeak' from the rear. Considering age of vehicle I would have the rear shock bolts torqued to 400 ft lbs (spec) and grease drive shaft yolk. Good things to do anyway.
Progressive torquing of leaf spring mounts and silicon can't hurt either.
Progressive torquing of leaf spring mounts and silicon can't hurt either.