I'm not sure about what comes apart under the dash and with all of the electronics in these trucks I can't afford to watch something start smoking. The old days you just ran wires wherever they could go and mounted things into metal dashes. This is a whole new world trying to not mess up the plastic. Not looking for a quick fix but I'm not familiar enough with this platform yet.
As long as you use a 12v test light.. and find a 12v source at/in the fuse block.. that is OFF with the key OFF.. and a good Ground.. yer good to go.
If you look around under the dash.. yul see where FORD Grounded stuff... back off a nut and use one of those Grounds ?
As far as where the CB gets mounted.. thats your call.. based on ease of access.. and the look yer after... taking in the Mic ease of access too. Each Year, Make, Model, and accessory packages.. Makes it real hard/impossible.. for any of Us.. to tell You where... will work for you (?). (what Dave said)
That grommet on the fire-wall is easily used as a place to run the antenna wire through. Amazon.com sells an antenna wire that has one end the "brakes down", so to speak... makes it Very Easy to push the wire through.. from the under the hood side.
Joe
Jus' An Idea ? Those CB's with a power module.. with the controls on the Mic [could be].. mounted under the seat ? Outa sight ?