redwoodguy, GM likely has a tech brief on installing two way radio transceivers in their vehicles.
The DODGE one (likely little different) is
here.
Mounting the antenna is a bit of a challenge as one has to drill the roof with a hole cutter, mount a "puck" style mount underneath, and seal it up well. That said, the "competition CB" guys all use Subs because of the huge roof (and because they're also running two- three alternators as well).
CB stuff is a bit arcane, and subject to endless circumspection. A C-29 that has been peaked & tuned by a well-known tech, and a first-class installation of the power plus coax plus antenna tuning makes for a great set-up. Just hard to find someone to do it.
HAM and other radio guys are really your best bet. Your vehicle is an easy one to deal with, overall. You might try ARRL to see if someone in your area can make recommendations.