Black/White from distributor +
Blue from distributor -
Black/white harness (ign.) +
Small brown (tach) -
Large brown (starter?) +

When the ignition key is turned to the start position it cuts power to the entire truck. The coil then gets its power from the starter while it is cranking. I'm guessing that the larger brown wire is from the starter.

There should be a ballast resistor also that is missing, although that is not your current issue. There's a good chance that not having the resistor burned up the igniter in the distributor originally.