What would the easiest way to mount a 4 foot firestick vs a 102 whip on a CUCV? I don't know much about CBs...
What would be the performance/range distance between the two antennas?
The whip is gonna need a strong mount , since its going to hit stuff alot more than the fire stick ( taller) , something like a good solid bumper mount. If you mount the fire stick high and it hits, your gonna need a strong mount to, and maybe a spring on it so You dont break the fiberglass or the mount.
as far as signal 2 things....
First, placement on the vehicle. if the antenna is mounted in the center of the vehicle, it will give a somewhat even range in all directions for the most part. If the antenna is moved to the rear of car, it will tend to get more range towards the front of car, and vice versa (left and right too). The metal body of the car helps radiate the power from the antenna in that direction (non metalic things like fiberglass camper shells dont count)
Second, a coiled antenna firestick) might have a 1.5 db gain (decibels), where as a 1/4 wave whip might have 3 - 3.5 db gain (this is a rough guess , look on the package of the antenna for an ideaof db`s ). The rule of thumb is that for every 3 db gain that You have, it roughly doubles the range of the antenna.
The ham motto----- a radio is only as good as its antenna,
Hope it helps