Hey Paul WNC.
I think I can cover this one. Here is a pic of the ammeter etc.
http://i1293.photobucket.com/albums/b585/Milibolt/Electrical%20systems/IMG_1612_zpswdx5gppt.jpg from the dash of my spare cab. It apparently has the original harness and while somewhat brittle, is quite complete. The wire you see coiled up and marked "filter rt. side" or similar is the wire you are referring to. I marked it and perhaps it was connected to the filter when I got it, but it's over 4 feet long and has a 3/8 inch ring which I would think surely would connect to the starter (bat) lug which is shown on our schematic for these rigs.
It's a fatty. I measured it with my venereal calipers as follows. .270 around the insulation, .145 around the conductor itself (I didn't want to peel off more insulation so I measured it in a small area near the ring connector. The ring as mentioned before is 3/8 in.
Hope that sheds some light on that one question anyway.
BTW is it just my computer or is "photobucket" extremely slow these days. Man ! Just chunks along. Probably my machine.
