['68OrangeSunshine]

Usually with a stubby CB mount you wanted a coax length of 16' for better waveform resonance.
I have a '68 C/10 Stepside, which was once a fleet truck for a municipality, commercial entity, railroad or even CalTrans. It once had a VHF 2-way radio. It has a rubber grommet in the center of the roof where the short masted antenna was. There are old screw holes running from just over the cab light, past the passengers' head and down behind the seat. It would then be run under the rubber floor mat to behind the radio. The radio was mounted under the heater controls.
I bought the truck in 1973. In 1977, I mounted my own CB. I cut a 1" hole on the rear of the drivers side step fender for a ball mount and M3AD heavy duty spring, and ran my coax from there, along the lower frame and came into the cab thru a 1/4'' hole in the floor, under the rubber matt and into the back of the transceiver. Antenna was a Hustler fold-over mast with a load coil and a 3' or 4' "radiator" [whip]. Rig was a Realistic TRC 421 with a Plus-modulator mike. Got out real good, barefoot. My mast was retractable [manually] so I could get thru low overheads when necessary. It was about the same length of a 1/4 wave whip.
My old coax is still in place.
I just hooked up an SSB/AM CB rig that I'd bought in '96 to put in my [then] new '71 Jimmy and then totally forgot about [ after I got the first cell phone that year.]
I bought a pair of ''Rabbit Ears" [Twin Trucker Mirror mounts] to finally put them on the Jimmy. Right now it's temporary in my '92 Subaru, with a stubby magnet trunk mount.
Needs final tuning of radiator* whip length for optimization.
* We're not talking about the cooling system. Top or whip is called the radiator since it radtates your signal.