It's probably a 18WXSTII. I've had one for a few years. Good little radios for a plastic box Cobra.
You have to have a good SWR (1.8:1 or less) to actually get any use from the ST (sound tracker) feature otherwise the reflected power forward biases a diode in the ST circuitry and locks up the radio. The weather stations are nice to have, especially if you are offroading where you can't get alot of radio stations and very few stations carry the weather regularly anymore. I gave about $70 for mine new. It's a good little trail radio and I've talked about 18 miles off the weak side of my Jeep while mobile to a strong base in town.
All in all, I'd buy another one for a trail rig, but if you were going to do any serious CB talking, I think I'd look elsewhere for more features and more upgrade-ability.
I run mine with a 102" whip on a 6" S/S extension. I've also had it running through a Wilson 1000 Silverload fiberglass antenna mounted in the same spot, but broke that antenna off and went with the 102".