backup light switch.

OEM switch isn't the problem. Its the actuator pin sticking out of the column that can't be found online at reasonable price. Here is a pin for later model...
PN 2883211 reverse lamp switch trip pin for 1967-68 Plymouth Barracuda - Belvedere - Fury - GTX - RoadRunner - Satellite - Valiant; 1967-68 Dodge - Charger - Coronet - Dart - Monaco - Polara; 1967-68 Chrysler and 1967-68 Imperial with column shift