1966 back lights wiring

[bonehead]

I need to re-hook up my reverse lights on my truck. I need to find the wire to the backup lights on my 1966 C-10. Was it originally activated by a switch on the steering column under the dash (3 speed manual originally) or was it activated by a switch on the tranny somewhere. I'm hoping the wire is still under there hanging somewhere. Just need to know where to start looking. What color is the wire? Any help would be appreciated.

Any ideas for a slick hookup, my trans was changed to a turbo 400 by the PO. Might just do a toggle switch under the dash if no slicker ideas work out.