379 coax cable ?

If it's factory coax. It would be better to replace it with a good qulity coax. The factory coax is junk. It takes alittle work but worth it.

 

I cant believe this is much different than my W9...but my CB is in the top visor along the roof of the cab.
The prior owner had it on the dash so more parts would need to be removed in that case..

I bought a kit, since if your run DUAL antennas you need 75ohm coax
vs 50ohm coax for a single whip...I could have bought even better raw
cable but then have to mess around soldering ends and getting both cables into
(1) PL-259 end. That's just a pain I think - was easier to buy a decent kit.

I dissembled the top of the windshield area and
simply used nylon pull string to attach to the old cable and then used it as a fish line to pull the new cable back out.
I could easily reach my hand up to and into the spot where the coax exits the cab on the passenger side but the driver's side had something in the way.

Pull string worked great.

 

You might be able to just 'feel' the cables too, with your hands..
Also, when I install the antennas, I make a really nice 'drip loop' in the coax
and then wire tire everything snug. The grommet into the cab was a bit
fossilized so I just used a bit of silicone to complete the seal.

Any extra cable left over inside, just wind into a race track (oval) and then squish it flat and wire tie it.
Don't make a circle with it and don't cut the coax differently on each side.

I just use a factory made dual-cable setup and tuck the extra inside the top
like I mentioned.