thing engine wiring

[mentalQtip]

Hi guys. I would like some help on some wiring in the engine bay. Apparently a couple of years ago I ran a "red" wire directly from the battery to the voltage regulator. I am sure I did it because I couldn't get the engine the thing came with to turn over. I later junked the engine.
Two years later I put another engine in and start wondering about the black wire that comes through one of the holes in the firewall on the right side, the one with the inline fuse. Where does it go?
I'm pretty sure that the red wire shouldn't be where I put it but am really unsure of myself here.

Any help is surely appreciated.

[Stray Catalyst]

That wire is for the reverse lights, and leads from a contact on the front of the trans. You can run the engine without it, but it's a bit more difficult to get an inspection sticker, unless you jury-rig a dashboard switch to run those lights instead.

Stray

[wildthings]

You should have battery power to the B+ terminal on the regulator. This should be a wire running from the B+ terminal on the starter. It could also come straight from the 12+ post and the battery and work the same.