After 1969, the sedans used a different transmission than the W113 cars. The neutral safety switch including the reverse lightswitching, is located on the transmission itself, at the linkage pivot on the left side. If it is out of adjustment, make sure the shifter bushings on the linkage rod are good. Typically the adjustment can be made by shortening or lengthening the shift rod itself at the turn-buckle on the linkage. Please relate that your transmission is the later "four bolt" style oil pan. W113 cars all used the earlier 16 bolt oil pan transmissions. Also, is your car column or floor shift automatic?