The neutral safety switch, depending the car year and model will be either in the tranny or on the steering collum, the starter relay that activates the starter solenoid from the ignition switch is usually mounted on the firewall
If its a manual transmission there is no neutral safety in those years. That terminal is soldered to the starter relay case for a permanent non-switch ground.
If talking bout the 74 OP’s truck, the manual transmission gets the ground but coming from clutch pedal switch instead the NSS. The pedal ground for manual transmissions began on 70 as far I recall. Not anymore soldered ground to relay chassis.
Anyway, the OP’s problem is not related to relay or NSS/clutch pedal ground
