Charging system wire around 6 or 8ga

Since you brought this back up to the top, I have a question. Forgive me if I've asked before, my forgetter works full time now. Is there someone who converts these ammeters to volt meters? I don't give a crap if it reads numbers. I can relate to it with the "D" and the "C". I'm just wondering is someone can basically stick a volt meter on the back of the stock face?

Yes, redline does it.

Lots of home builder guys have used some of the small voltemeters and installed them in the original clusters. If you search here or FBBO, there are some threads on the process.