Mike G,
I still am not clear on what rig you have! To polarize the generator you momentarily touch a jumper between BATT and ARM. The main wire from the ARM to voltage regulator is usually a 10 gauge wire. The book shows the field wire as only 18 gauge...that sure is small. I would use at least a 16 gauge if for no other reason than durability.
I don't know if you could find the brushes on the shelf at a parts store or not...give it a go. Good luck and edit your profile to show your truck model and year...it helps when you ask questions.
Stuart
