I think the adjuster, or whatever makes it take up space is missing and the lock tab.
how does the adjuster work? that is what unscrews to take up space?

I pulled the axles, to remove the drums and backing plates, and I replaced them with the tsm disc conversion kit.
I never saw a locking tab.
That area was gunked up with what I guess must have been caked up grease and some diff fluid.
I blew it all out with brake cleaner and then repacked the bearings with grease.

I think the adjustment plate is there, because it had the most crude caught in it. I had to use one of those straw attachments to clean all the stuff out of it.
It does not turn freely once I bolted the axle in.
But I didn't see any threaded parts under it.