Does anyone have a diagram of the original battery cable hookups? I am more interested in the positive side and how it mounts. I am starting to wonder if my setup is wrong.

 

Being a 6 volt positive ground it should bolt to the frame close to the battery. Make sure you don't have paint or rust at that point...

 

It should be connected to the engine, like the intake manifold. From the engine, a separate strap should go to the frame and another to the cab. Those don't need to be that heavy (#12 is fine).

 

That's what's shown in the parts catalog. The ground strap is part # FDE 14301-B and connects to one of the bolts which fasten the starter solenoid to the frame. There is another cable listed: FDA 14301-A which presumably is an engine to battery ground strap but it's unclear where it connects.