The closest thing to a military GMRS antenna that I'm aware of is a discone, too big for a deuce. There might be an aircraft antenna of some sort available but I don't know. If you need a GMRS, best to find a small one like the cop cars use and put it somewhere it won't show. It can be painted green if non-metallic paint is used, such as latex enamel. Since a GMRS antenna is naturally quite short at 4-6", even a military stub base with no whip would be too long. You can also make an antenna if you wish, it is not too hard for GMRS band.
If you want a CB antenna with no fuss, use the HF whip antenna with 3 sections, and make the top or bottom section the short type.
Use the AB-652 base, and this is normally used with the MS-116-117-118 MAST SECTIONS - each 39.3"L.
Instead of this configuration, do one of the following:
substitute an AB-21 - MAST SECTION, 27"L for the lower section,
OR,
substitute an AB-23 - MAST SECTION, 27"L for the top section.
The result is two 39.3" sections and one 27" section, so that the total length in conjuction with the AB-652, makes a very good match for the CB, just like a commercial whip.
The coax cable does not just screw on to the antenna. If the antenna end of the cable has a connector, remove it and strip/free up the inner conductor (hot) and the shield braid (GND) for a couple inches. I used RG-213, a high power and durable type of cable. You can use RG-58, RG-8, RG-213.
The antenna base mentioned usually has a screw terminal, and you will need to attach the hot conductor of the coax cable to that, and attach the ground shield of the coax to a wire lug and screw that to the sugar scoop mount. The coax shield should be soldered to a short piece of wire, and this wire goes to the lug, and should be soldered to it. This is so the shield will reach the lug. A star washer must be used for the ground screw to make sure the ground connection stays good. Once this is done, cover all exposed shield, wire, end of the coax, screw terminal, etc, with silicon glue. I'm glad this came up, because I decided to go take a picture to illustrate, and found some corrosion. Even though it still works well, it needs PMCS.