what's the wire for Frank? I'd expect any wire in the headliner area would only be for an interior light, tail lights were usually run along the frame, attached securely with clips
is the original wire in the headliner still there? if so you should be able to attach the new wire to it and pull it thru, usually wires there are just laying in the space along the side above the doors

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics