The Stovebolt Site Forums The Parking Lot Tons 'o Fun Single wheel AD rear axle swap: GM 14 bolt.

From my experience with 14 bolts, another option may be using the SRW 14 bolt (67" one) with the DRW hubs (either 63" or 72" one). The only difference in these is the location of that flange for the backing plate, the dually hubs vs. SRW hubs are what makes the width difference.