They're not hard at all to overhaul. Most parts like seals and such are available from the flaps (go to Napa for the gaskets, though). A manual is a good idea to have handy, or you could just print off the online version. A couple of tips, have a can of wheel bearing grease or Lubriplate handy, this is needed to hold the needle bearings in place when installing the clutch gear onto the mainshaft, and a bottle of Lucas Oil Stabilizer makes for an exellent assebly lube, too.
