Just grab your tool kit, head to the boneyard, find a ZJ with rear discs. Jack it up, remove the rear wheels, pop the pumpkin, pop the c clips, pull the calipers and remove them, pull the axles, unbolt the backing plates. I'd also grab some of the associated hardware like any clamps, hoses, cables. I'd for sure grab the calipers and use them as cores for a new set, I'd probably go with new top hat rotors too as well as new pads and shoes. Again jeepsareus has the rotors, shoes and pads for $129 which may not be that bad by the time you piece the parts together from from the store. I'd also go with new hardware like springs and retainers. It would also be a good idea if you take a few pictures of the disassembly for reference. Do a search on here, someone actually put the correct part numbers for all the pieces you need a few months ago. The jeep parts finder lists 95-98 for those disc/drum rears.
While I was hunting thru jeepsareus.com I came across new factory backing plates last week, $35 ea, new.
