what are these wires ? 1972 dart 318

1970 and newer mopars didn’t use a ground strap from the back of the engine to the firewall. They had the extra wire from the battery cable to the core support to supply ground to the body.

Your photo looks like a wire on the bellhousing bolt. But it’s hard to tell. Do the wires keep gong down below that bellhousing bolt?

Uh, my '74 has one. Passenger side rear head to the firewall. Cute little flat braided ground cable. Looks factory to me, but, maybe someone added it a long time ago.