If I recall, There should be a fuseable link, It should be at the battery, or somewhere up at the firewall. Its been a while, but I think there is 2 wires (or more) coming the positive side of the battery. The heavy one supplies voltage to the starter, the thiner ones supply voltage to the rest of the truck, there may be a 3rd going to the alt. Make sure the one going to the truck is not open somewhere near the battery using a cheep test light.
If there is not a wire coming from the battery to the truck, then it comes off the starter. See if it did not burn off on the exhaust manifold.
Also there is a ballast resister near the center of the firewall. It has 3 or 4 wires going to it, its white porcelain looking thing with 1 3/8 bolt holding it on the firewall. These are known to go bad on a dodge. This will make it crank but not start.
Hope this helps some.