On my L code project, I've got 3 wires I don't know what they are. The first two are passing through the firewall, one right of the vacuum lines, and the other with the main harness group.
The third is near the starter solenoid.
My 6cyl was blowing smoke since I bought it a few months back. I opened it up last weekend to replace the valve seals, only problem was, THERE WERE NONE!
No seals. After I got finished, no more smoke.