I am finishing up a 3/4 ton 14 bolt disc conv on my '71 Suburban and I used Cadillac Eldorado rear calipers w/ e-brake (bought on ebay), '71 4x4 front rotors, and I found a guy (via ebay) that used a waterjet cutting unit to cut some brakets to my specs, sent him the caliper and the bolt spacing for the rearend so I could bolt mount the brackets.
Looks good and is perfect for my 16" wheels