What I did was run both the batt (#10 red) and alt (#10 black) wires right through the firewall on my 72 bypassing the shitty bulkhead connector altogether. I did used grommets to prevent chafing of the wires.
Nate Breece
North Chesapeake Bay Vans
1994 Dodge B250 Elk Conversion (5.2L/A518)
2008 Dodge Caravan (3.8L)