i found a N/S switch for my floor auto shifter here an sure wasnt 400.00 bucks
shiftworks.com the switch also has the back-up light switch with it. i made my own wires but the do sell the harness. i have 1500 miles on the car since the install an all works perfect.
Is this what you're looking for? Took it off of my power glide. Not sure if it works. Don't know how to test it. Powerglide is long gone and this was in a box of stuff in the garage. No part number on it. Says Delco Remy and 618 or 819 depending on which way you turn it.