corwyyn wrote:
What the dual antennas do is narrow the pattern of the radiated signal and concentrate it along the path that is perpendicular to the line that connects them, so if you mounted one on each side of the Jeep the signal would reach out further toward the front and back. The problem is that you need a quarter wavelength (9 feet) between the antennas to get the best out of the setup, and the KJ is not much over 6ft wide

I think I'd go get another length of coax and a single connector and just use one of the antennas and have a spare.
SEND IT BACK. get a high quality 18 ft coax cable and atleast a 2 ft 3 ft would be better fiberglass, firefly tunable antenna an then mount it so as much of the antenna is above the roof as possible and have the swr tuned and thats all.
send the dual back, wont work on ur kj.