I have 2002 Road King and had the same issue with the noise also the bike would go into any gear but the grinding sound would happen when you released the clutch but the bike would not move forward in any of the gears my problem was the transmission sprocket part #40210-85D it cost $149.50 its located in the primary cover, the drive belt runs around the outside of the gear and is driven by the transmission shaft in the center of the gear, the inside grooves of the gear where the transmission shaft goes were stripped on my bike and couldnt drive the belt forward, the service advisor at Harley explained that if the compensator nut was not fully torqued could cause this issue over time, If this sounds similiar to your problem be sure to check transmission shaft when apart, mine was ok and most likely yours would be too as the sprocket appeared to be made of a softer metal than the shaft of the transmission. If you have to bring it in to have it repaired it was a $600.00 repair