Welcome. 89 v6 5 speed gas mileage won't be that great. IIRC probably 18mpg on the highway at most. don't recall a city mileage. Realize it's the shape of a big brick so you don't have much aerodynamic advantage with it.

I purchased a relatively clean 89 v6 automatic for 1500 a few years back. It had stock bumpers, & was the RS model (no power windows or door locks, or LSD). Paint and body were in pretty good condition with no rust to speak of and it only needed a good clean and polish to get rid of the paint haze/oxidation that had accumulated from years of sitting in the sun.

As for bull bars, IMHO other than being purely cosmetic (I check posers at the door <img src="/forums/images/graemlins/lol.gif" alt="" /> ) they can actually create more damage than if you didn't have them to begin with since they will bend into your vehicle in a mild or greater collision where without them the most damage would have been a bent up bumper.

When inspecting the vehicle, check for leaking valve guide seals by letting it idle for 5 minutes or more then quickly revving the engine. If you see a cloud of blue/dark exhaust, then they're leaking and at some point will need to be replaced and until then you'll have to check for lost oil on a regular basis.

As for long term reliability, the engines are about as reliable as most Japanese engines. Mine has over 170k on the ticker and still doesn't have the dreaded leaking valve guide seals (knock on wood).

Other than the valve guide seal issue which is not a critical one these are very, very reliable rigs and quite capable off road (more so than most 4x4's).