I don't know what's on Ebay, but I believe my outboard drive axles are 7/8 in dia so they may be the same thing. I do wonder where mine came from.
A small update of this minor saga FWIW: After disassembling and re-assemblng both L & R sides, I'm fairly sure both the axles and the Special brakes were a PO mod, competently done on the L side, less so on the R side. Much of the problems there result from an incorrectly drilled cotter pin hole in the R drive axle (i.e., too far inboard). A thicker spacer would have fixed a lot of problems with drum and back plate interference, only that isn't an option as a thicker space would cause the castellated nut to "cover" the cotter pin hole. And grinding the backside of the castellated nut doesn't seem like a good idea to me and, apparently, not to my PO.
So, my PO used an "undersized" spacer on the R side so that the castellated nut would fit but then had to have both the brake backing plate and the drum relieved at their outer edges to allow the brake drum to fit closer to the back plate than normal without interference.
Funny thing is, the spacers on the L and R are the exact SAME thickness. Ignoring for the moment the cotter pin hole position, one would think the spacers would be essentially the same thickness as all the parts (hubs, drums, back plates) appear to be the same, L to R. I'm unclear why the R side spacer should have been about 1/8 inch thicker with the cotter pin hole further outboard.
Bottom line out of all this is, if you have the std 1.25 " brakes, I would keep them as the Special brake parts (drums, back plates) appear hard to find. I'm still looking for a new or near new brake drum to replace my RR drum as it is at the max dia limit and can't be machined. If anyone knows where these can be had, please let me know.
What should have been a simple brake job has turned into a real pain and has really pushed me to consider adapting disc brakes at the rear.
regards
Rick