[05crewcab]

Sure, in stock form, there are two wires from the fuse box that go to the starter. a solid purple wire, and a purple/orange wire. The purple/orange wire T's with a yellow wire before it hits the starter. that yellow wire goes to the coil for the old points distributor system. With HEI, there is no coil, so the yellow and purple/orange wires are not needed any more...you can just cut it off at the fuse panel and toss it. the reason for doing this is the puple/orange wire is a resistance wire, and will get super hot and melt if left connected with no coil.

Now, having all that said, the truck is 40 years old and has probably already been butchered a bit in the wiring department, so your wires may look different....as long as your finished product looks exactly like the diagram above you'll be set:

New 12ga to HEI from ignition unfused in fuse panel (red)
Existing 12ga to Starter from fuse panel(solid purple)
Existing 6ga positive battery cable to Starter from battery (Thick Red or Black)