I'm putting together a 1970 GS steering column, manual transmission, installing a reverse light switch, and see that the Factory Assembly manual calls out a different part number for manual verses automatic cars (3943657 for the manual transmission, 1993456 for the automatic). It sure looks like I can us the automatic switch, 1993456, which I and most of us have (since it's an automatic part)? The manual transmission backup-light plug in the dash harness (green and pink w/black tracer) plugs right into the backup light prongs on the automatic switch. The manual back-drive rotates the column collar when shifting in and out of reverse. I suspect a difference could be if the manual back drive rotates the column collar a different amount than the automatic?