A lot of splicing went in down there. Not good.
That's a pretty typical problem for the Fuselage cars. It's the battery feed for just about everything. It was a poor design to begin with and I've never seen a Fusey that didn't have the burnt connection here.
The best repair is to bypass the connector with the red wire. Snip the wire on both sides of the connector and connect them together with a crimp on butt connector or solder and heat shrink. You may need to cut the wire back and add a short piece of #12 wire.
The other wires and circuits through the connector don't have this problem.
If you want to take that connector apart and repair, you'll still want to bypass the connector for this red wire. Too much current passes through it and the problem will reoccur.
A 6 pin (3x2, not 6x1) 10-12 guage M&F Molex, AMP, et al, connector is all you're going to find.That's true that if you have to replace the switch, you'll have to do something to get the new connector to plug in to the old one. Even getting the old one apart is going to be difficult. I would still strongly recommend doing a splice for that red wire even with a new connector.
That said, I don't know if anyone makes a replacement connector for this. I don't think I've ever seen one.
I'd seriously consider a Delphi Weather Pack instead.A 6 pin (3x2, not 6x1) 10-12 guage M&F Molex, AMP, et al, connector is all you're going to find.
Myself, I used two 3 pin pairs.
Caution: Radio Shack Molex connectors are 14-16 I think. power. 10-12 are internet items.