Thanks guys...
I was really hoping that the early KX hubs were the same as/similar to later KDX or KLX, to be honest. I was playing my cards close to my chest in case they were close but not identical - if that had been the case, I'd have kept my mouth shut and fitted one to the bike...
Anyhow, a mate sent me a parts diagram, and they're miles different to the early KX bits.
The bike is an F11 that I'm figuring out what to do with - and the original wheels are pretty scary.