I like the First Generation (1G) Troopers from '85-'91 because of the shape and size. My preference is the '88-'91 with 2.6L EFI engine (4 cylinder, 4ZE1) with the manual 5-speed tranny because it's pretty zippy and efficient. I still get 20mpg highway with over 200k miles on the odometer.
The axles on these trucks are geared 4.56:1, and the Isuzu 12-bolt rear axle (not to be confused with the GM Corporate 12-bolt axle) is tough. Plus these 1988-1991 trucks have 4-wheel disk brakes--much earlier than most other manufacturers put 4-wheel disks on their trucks/SUV.
Some models came with a limited-slip rear end, too. Look for option code G80 on the data plate on the firewall under the hood, drivers side.
A possible down-side to the 4ZE1 is the head gasket; Reputation is that the castings were poor early--and were corrected in later productions. You will find the casting number, 1 through 6 IIRC, on the head near the "4ZE1" casting.
I replaced the head with an aftermarket unit about 4 years ago when the gasket blew. Probably could have simply replaced the gasket since I'm certain there was no over-heating involved.
If I were looking to buy another 1G Trooper, I would be most concerned about rust or corrosion in two places: first in the bottom seal of the rear doors, then under the hood at the battery tray I'd recommend checking the side windows and windshield weatherstrip, too, but of less concern because those aren't "typical" spots. Of course you want to check the frame rails where suspension and body mounts are located.
The 4ZE1 will last many many years with proper maintenance (oil, filters, timing belt change at intervals). I'm over 200k miles with mine and several on PlanetIsuzoo have exceeded 300k miles.
Depending on location and vehicle condition, running 1G Troopers can be had for less than $2000. Most I see are in the $1000-$1500 range. One often sees "needs head gasket" classified ads for cheap, say $500. There are lots of budget-built Troopers out there. Very reliable and quite capable, too.
Good luck!
