A freewheel, not a freehub (+ casette)
Sheldon Browns site seems to suggest with 2 chain whips you can remove the threaded sprockets off a freewheel. I realise I'm not going to be able to get new ones indivually, but If I could (is this possible on all freehweels? mine is pretty low end), then maybe I could knock up some spacers somehow and re-use one of the sprockets to use a SS freewheel
Else are threaded SS sprockets (to go onto threaded SS hubs) then same thread as (shimano) 7spd freewheels?

