Yeah chris-
Bender racing would be your best bet for some old school Yamaha parts.
They used to make LOTS of stuff for the ol' exciters/exciterII's-Wide kits,
stiffer stabilizer bars,willwood hyd.brake kits,fox shock upgrades...etc.
Never heard of a 596cc exciter-do you mean 569cc??! or is it a big bore.
Anyway-good luck-they may have stuff for ya-if you call them, ask for
tim or terry-they may know about more old stuff thats sittin around
waiting for you????
Also-maybe haucks?-Riechards? they have been around a long time too.
-Matt