Is it a pickup, or a troop carrier? It should have the H motor, which is an excellent motor, but somewhat underpowered. I have the 2H in my troopy, and you can still feel why a turbo would come in handy. Are you sure about the five speed? From the factory it came with a four speed, probably an H41 which is great offroad, but still limits your top speed on the freeway. My H41 likes to do 65 MPH comfortably, with 32" tall tires, at just under 3000 RPM. At that speed I get close to 30 MPG, and overall I get around 25 MPG US. The only problems I have had were with the front propshaft, which had a toasted slip joint and was ready to fall off the truck (yours should have the double cardan joint like mine), and the steering was and still is somewhat loose. Half of the play was fixed with new tie rod ends though. Also, these motors don't come with altitude compensators on them, so if you travel above 7000 FT and put your engine under load, you will pump out a thick carpet of black carbon. Despite all this, it has been an absolute blast owning the troopy. It is hard to imagine a 4X4 I would enjoy more.
Regards,
Scoot