Truck dead in the water

[EMCustoms]

I have been working on my brother-inlaws 73 F100 for the past 6 months getting it road ready, I replaced the following items; ignition switch, coil, starter relay, battery. It is weeks between the time I work on the truck since I live 100 miles away and never had any problems getting it started. The last time I worked on it I fixed all of the lights then parked it. When I went back the next time the truck acted like it had a dead battery so I checked the battery and is still good, it seems there is no power getting to anything past the starter relay; the lights and horn won't even work. I am new to this truck and have looked the the wiring diagrams but am lost at were to start, any ideas will be helpful.

[Hemmi06]

Check the cab power wire. (Black with Yellow stripe) with the work on the light may have shorted. There is a fusable link in there that could have died. Also how is the Volatage Regulator?

[EMCustoms]

The voltage regulator looked original so that was my next thing to replace. I wil also have to check the power wire. Thanks for the info.

[fordman]

check the connection on the starter relay where the positive battery cable hooks up. it could have lost contact for some reason. that is where i would start anyway. yo udo know how to cross the large and small terminals to start the engine?