Car Starts in Gear

"Why not" just use the NSS that is ON THE TRANSMISSION and likely worked "fine?" In other words why did you change it? The original NSS on the trans has one terminal (the NSS) up through ?68-or69? and then changed to the 3 terminal one. The one wire simply goes over the trans, up the firewall, and to one of the "flag" push on terminals on the relay. You are done.