With modern vehicles it has become difficult to find a spot for a CB radio.  Traditionally, a CB was mounted under-dash.  However most vehicles now have a center console which makes an under-dash installation impractical if not impossible.  There are no specialized mounts available for mounting a CB in modern vehicles. 

Here are a few suggestions:

ON THE DASH
You might consider mounting the CB on top of the dash.  Just be sure to properly secure it so that it does not become a projectile in the event of an accident.  Before mounting the radio, check whether state and local ordinances forbid mounting items on the dash.

FABRICATE A MOUNT FOR THE CENTER CONSOLE
Depending on the layout in your vehicle you might be able to mount the radios somewhere along the center console.  You will need to use your imagination and ingenuity for this, because there are no commercial mounts available. 

LAY THE CB ON THE PASSENGER SEAT
This is workable for temporary use, but only if you do not have a passenger!  You will want to prop up the radio so that you can see the front panel and also so that the speaker is not blocked.

CONSIDER THE 75 WX ST
The 75 WX ST has all the controls in the handset, and there is just a small junction box for connecting power and antenna. The junction box easily fits under the dash or under a seat.