Colin. Browsing previous Frame posts I came across this, looks to have stumped most of you and been consigned to the other file marked other guy's problem.
Bit overdue now but to me it looks like a late model A65 hub, with a single bearing locking ring and external thread to take a speedo drive assembly. Just the thing for running a repro Indian Speedo from the rear wheel rather than the A10 Gearbox.
Typical part no 68-6114 from 1966. Bearing retainer is 68-6081, RH Type 2, but check thread as they did change.
If it was offered as a straightforward bolt on for a Plunger bike, no chance, it's from an entirely different model range. Should fit with homespun spacers etc. and a bit of lateral thinking.
Any help?
Swarfy.