[Excaliber]

Could be the pilot bearing/bushing is to tight a fit on the input shaft of the trans, assuming the clutch is fully releasing. SOME grinding when shifting into reverse is normal with a top loader, reverse gear is straight cut, non synchro. I usually apply gentle pressure to second or first with the clutch depressed to STOP or SLOW the trans gears from turning AFTER I've all ready depressed the clutch. Sometimes I depress the clutch and simply 'hesitate' to let the formerly spinning gears 'slow down' before I shift into reverse. If the pilot bushing is hanging on to tight to the input shaft (or the clutch is not fully released) it WILL grind in reverse no matter what you do. While the synchros will 'help' you shift smooth if the clutch isn't fully released (or the pesky pilot bushing again) you will at the very least be placing a heavy load on the synchros and wearing them out prematurely. Actually there pretty cheap, I would replace them no matter what if I took the trans apart.

"David Kee" for top loader parts is one excellent source. Simply 'Google' it and you will find him.