take it to a shop and get an "estimate" they will look at whats wrong, and give you an estimate which should show what they need to fix, this should all be free unless you decided to do the work there

sounds like somethings off. rear brakes adjusted correctly ? grease on any of the rotors ? what kind of pad material ? were the rotor's turned or replaced when pads were put on ? what did the rotors and drums measure out at ? My stock brakes on my 99 jeep slow my jeep down fine and will lock up my 35's if i brake hard enough.
There are kits out there to convert the rear drums to disc, but thats not going to help braking much. Drums actually stop very well in the rear of vehicles, the swap to disc is more for convenience etc. They do sell a very nice "big brake upgrade" kit for wrangler's front brakes but its about $600 i believe
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- 99 Silverado - retired to spare vehicle
Black headlights/turnsignals/taillights- 6K HID Low beams, back on stock rims. current project/DD 99 jeep TJ