[LS short box]

On all the LS swaps I've done I've purchased an aftermarket harness. The aftermarket harness supplied the single wire to the 2002 Camaro type alternator. I use Fbody accessories.
I don't run the large gauge wire to the alternator from the battery. I run it from the large stud on the starter.
On the older hot rods I've LS swapped I have replaced the original vehicle wiring harnesses with Painless wiring harnesses because I just don't trust 50 plus year old wiring. Also keep in mind any late model alternator has about 3 times the output of the original alternator.