UPDATE 5/3/2011
Here is a writeup of what I did to convert my 1991 Dodge Colt to rear disc utilizing 1992 sedan hubs.
Pictured below is the C52A rear axle stub. Note the 1/2" section that is a larger diameter than the rest of the stub which when using the C53A rear hubs acts as the bearing surface.
Pictured below is the inside or bearing side of the sedan hub. Note the sealed bearing does not have a taper like the axle stub.
Pictured below is the sedan hub bolted up tight to the rear axle. Note the hub bottoms out on the face of the 1/2" bearing surface.
The C53A rear disc bracket has an offset so that the caliper bolts up to the bracket on the same plane as the bracket bolts up to the rear axle.
Pictured below shows the 1/2" thick caliper bracket I made for the sedan hub.
Now with the bracket figured out calipers were required. I opted to use FWD DSM rear calipers. I was fortunate to find a car at the junkyard that had remanufactured calipers on it with nearly brand new pads.
Pictured below are the refinished caliper brackets and the brake line bracket.
To accomodate the brake line bracket I welded nuts to a plate and then welded that plate to the beam as pictured below.
I didn't take pictures of the e-brake cable adapter I made. 89mirageman makes a great adapter for this purpose.
Pictured below is the final product.