2004-2005 660 Yamaha Rhino Factory Service Manual, Page 217Get this manual
MIDDLE GEAR
REMOVING THE MIDDLE DRIVE SHAFT 1Straighten: punched portion of the nut (middle drive pinion gear) 2Loosen: middle drive pinion gear nut NOTE: Secure the middle drive shaft in the vise with clean rag3 Remove: middle drive pinion gear nut middle drive pinion gear shim(s)