Well must admit this looks to have stumped most of you....unless you've been out to your bikes and thought that looks like bad news.
With a bare hub there is plenty of scope for a good strong welded repair, nuts and bolts being a sign of trouble if Trev's correct.
For mix'n match, Plunger and S/A crinkle hub wheels use the same wheel bearings. The bearing spacers are indeed different, as the spindle diameters are not the same. Plunger hub has two bearing locking rings, S/A has just one, on the chainwheel side.
S/A centre tube is shorter, so the shell cover on the end is flat, on Plunger Hubs it is distinctly domed. Easy to tell the wheels apart, look for the shell cover, or if this is missing, you'll see the bearing and no locking ring thread (S/A) or the locking ring on the plunger. If some toe rag has already had the ring, this will expose the LH thread on the plunger hub. Centre tube on Plunger Hub also sticks out a little further than the end of the crinkle pressing. S/A hub, they're almost level.
Swarfy.