Since it completely bypasses any type of neutral safety or starter bypass circuit, it can crank in ANY gear selection and in gear with a manual OR automatic
Rusty, your cautions of safety are something we all tend to overlook BUT...
My NSS provides power to where the yellow (IIRC) wire (67 Dart with a 273) on the starter relay goes and mimics the start cir of the ignition switch. it still relies on the NSS for ground to activate the relay.
Not trying to be a dick just want to be sure I'm not missing something, later years do it different?. ( IIRC old Fords use a positive side NNS)