CB antenna question for an old timer

[Mmorgan32]

So back in the 70s maybe when the saddle bags where installed on my truck there was a CB in my truck. I was told by the previous owner ( who bought the truck in 76) the truck didn't have a radio it had a CB mounted in the dash. The handset holder clip is still mounted to the dash. My antenna is mounted to the roof.

My question is does anyone know where they might have run the cable? I can't find it under the dash and I'm afraid of messing with the mount because it doesn't leak at all. Any ideas of where to look?

Btw there is no more CB radio or antenna just the mount. I'd like to put an old looking one in