Here's photos of the Wagoneer drum before machine work.
Distance from axle flange surface to edge of friction surface (3 3/16"):
Same measurement on original drum (3 1/8"):
So, there is only a 1/16" difference in this measurement between the Jeep drum and the original. For sure, I'm not going to have a clearance problem with the backing plate.
The reason I earlier said at least 3 1/16" was a must was because on the original drum, I could see that the shoes came to about 1/16" of an inch from the edge of the drum.
Again, this same measurement on the 2067DGS was 2 7/16"
I'm going to try and get these new Jeep drums down to the machine shop on Monday.