For disc brakes you'll need a 96 or newer Explorer rear. Bear in mind I haven't put it in yet, but I know there'll be some cutting and welding involved to make it fit. It's not a bolt in. Here's a good article from Ford Truck enthusiasts that's good reading. About 1/2 way down there's info on Explorer rear ends.
1948 through 1960 Ford F-1 and F-100 Rear Axle (differential) Swaps .: Articles