The Trooper only went through two generations during its 22 years of production. The first generation was sold from 1981 until 1991. The only engine available was a 120 horsepower I4, which was considerably weaker than what the Trooper really needed. This vehicle was good for getting down the road, or even small amounts of off-road duty, but I wouldn't go rock climbing with one.
The second generation Trooper showed some considerable improvement. The engine was upgraded to a 175 horsepower V6, with an even more powerful 190 horsepower V6 with DOHC also available. Later models (after 1998) could be purchased with a 215 horsepower engine.
Some Troopers were sold as four wheel drive models. Rear limited slip differential was an option during some model years, while skid plates were made standard.
These SUVs are very common on the used car
market. Check to see if any are listed on eBay before you go talk to that sleazy guy on the local used car lot.