well, hell! My GN is redone with Caspers' fusible link relocation kit so the memory wire has been moved and does not apply to a regular car and my T is up in the air with an engineless stationwagon under it so I cannot get to it.
The factory shop manual shows the fusible link feed being a 1 on the diagram which I believe relates to cross sectional area and I think a 1 would be a 16 awg. The alternator wire shows to be an 8 which is a hair larger than 8 awg according to this link
https://diyaudioprojects.com/Technical/American-Wire-Gauge/It's hard to measure the factory length because it is routed down under and around the timing cover and back to the alternator. If I were to make one, I would think about going a more direct route across the top if that is feasible.
Casper's hd version uses a 6 awg as I recall. I have one on the T and it was getting on the verge of being hard to route down and around....sorr
y, I am not any real help