Drums to disk
There is a company called J.C Whitney or Jegs that can help you with that.
But why? 80% of your braking is done by the front brakes.
All in one kit, everything you need.......https://lmr.com/item/LRS- 23208792-K/1987-1992-mustang-4-lug-rear-disc-conversion-stock- axles
If you decide to do a complete 5 lug conversion try sourcing a wrecked 96 as all parts swap over to the foxbody including the rear disc brake setup.
Looking for a Used Mustang in your area?
CarGurus has 41,405 nationwide Mustang listings starting at $900.
Search Ford Mustang Questions
Ford Mustang Experts