Originally Posted by
Hondo6
Did some further checking.
The Trek doc above says the hubs are "Shimano Acera X Parallex". The only "Acera X Parallex" rear hub I could find reference to was the FH-M290. All versions of that rear hub seem to be 7-speed HG hubs only.
OP: can you find a model number on your existing rear hub? For that model, I think the model number was on a sticker on the hub barrel.
Very nice photo and great bike to maintain! Good luck with your work.