Sounds like you understand the situation as well as I do.
I'll add that the backing plate and shoes and all that hardware are the same for single or dual wheel.


The axle housings differ in where the backing plate flanges are welded on depending on what hubs and drums.
Knowing this I did some measuring of various 14 bolt axles and tried to determine if there is an axle housing either cab and chassis or single wheel while also considering different brake options... That when used with the dual type hubs (to give ~63" track width) and using shallow 13x3.5" drums would have the backing plate in the exact right place.
I didn't find a combination that seemed useful. Best option was the C&C housing and make spacers, or weld new flanges on the housing in desired location.

If making a spacer I'd want something almost like these (at whatever the right thickness is). As shown they don't pilot inside the backing plate like the original flanges do, this detail I would want to duplicate. http://www.cutthroat4x4.com/catalog/product_info.php?products_id=63

Or I thought it would be easier to salvage some flanges off a junk axle housing, cut off the tubes and bore out the inside/cut the weld until the flanges fall off. Then one method is measure with dial caliper adjusting new flange parallel with original flange (use all-thread and nuts to position) also at the right spacing. Or install the hub, position flange in right location and use a dial indicator to adjust the new flange for zero run-out while turning the hub, tack weld and check and weld and check and finish welding and check run-out.

Grigg


•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-