[jhv48]

Solution to the grinding in reverse problem:

It took me two months of trying different fixes but it was a defective pilot bushing. For some reason, it wasn't allowing the input shaft to stop rotating when the clutch was disengaged so there was no way to stop the internals from spinning with the clutch in.

Replaced only the pilot bushing and reassembled the drive train with all the old parts and the shifts are effortless now.

$15 part cost me $1000 to diagnose and fix!