i have a 1972 f250 2wd cs 390 auto the po said the voltage reg went out
i replaced that still no crank thought maby crossing solenoid terminals would at least crank it and it went click so i replaced starter it will crank when you cross the terminals but not with the key switch so i replaced the switch and still no crank headlights wont come on nothing electrical seems to work so i really am out of ideas any help would be appreciated thanks

by the way it has a place for 2 batteries dont know if it was for the camper or not

 

sounds like the solenoid is your problem. Good luck

 

There is a power lead from the starter soleniod that goes to the fuse panel inside the truck(to power everything). Make sure it's on the BATTERY side of the soleniod. Sometimes people loose track and put it on the starter side and that won't allow anything to work.

If that is connected properly, then you need to trace power to the fuse panel. Anything? I think there is a fuse link in that wire at the soleniod(you'll see a black lump in the wire), and could be blown. Have to cut that out and replace it with new one(available at any parts store).

Once you get power to the fuse panel there will be more checks to follow if you still don't get any starter.