Just picked up a 74 DT360. I am trying to find the wires that go to the battery. I have 1 fused red wire that's probably the positive wire.I don't see a black ground wire. Can I used any negative wire? thanks 

Here's an image of under my seat (1974 DT360A).

Thank you so much I appreciate it

I'd just ground the battery to somewhere close on the frame not airbox or anything like that. That's if it has a ring terminal earth wire. But that's just me!!. Officialy i don't know. Check wire diagram online, might show a black wire or might show just to earth.

Thanks