You can get just the mounting parts, the bracket that holds the calipers, hoses, etc and remove the drum brake parts, the caliper bracket will mount to the original axle housing.
Your other option is to use a complete rear from 1992-1997 Ford Crown Victoria, Mercury Grand Marquis or Lincoln Town Car. The second option will also increase the width of the rear by about 1"(not much at all but some) and you will still use the original wheels.