I am wondering where the neutral position switch is located. My back up lights do not work so I am wondering if the switch has anything to do with it.
The Truck is a '79 with the c6 AT tranny, 351M

 

on the transmission with the shift lever (assuming it's factory)

 

So does the neutral position switch give the signal to turn on the reverse lights?

 

The neutral safety switch stops the car from starting when it is not in Neutral. its down near the floor pan on the steering column. Doesn't have anything to do with reverse lights.

 

That's not correct. The neutral start switch also includes the back up light switch, it's two switches in one.
The 73-77 models had the switch mounted on the steering column, under the dash near the firewall. In '78 the switch was moved to the side of the transmission. The shift arm sticks through the switch.
The first picture is the 73-77 switch, the second, 78-79.