Looks really nice! I just bought a '98 K1500, which is very, very similar.
Headlight circuitry is a weak point as there aren't any relays. Wire some in so that the headlight switch and multifunction switch don't have to take the load, or they will eventually fail. Both were actually bad on mine.
Front steering linkage tends to wear - a new pitman arm, idler arm, and idler arm mount is often enough to tighten it back up, and is a ~4 hour job.
That truck (and mine) is new enough to have EVO steering, which has a PWM valve that controls effort. They work well when working right, but they don't always work right. There are eliminator kits out there, or you can replace the valve for a bit more money.
New fluid really helped the brakes on mine. Still working on what pads to get. There are tutorials on upgrading to brakes from a newer model if you plan on towing/hauling a lot.
Vortec engine is mostly solid, but the heads are a lighter iron casting and if overheated, will crack between the 2-4 and 3-5 cylinders on up through the valve seats. Don't overheat it and this won't be a problem. Colder thermostats significantly hurt mileage, but due to the old american nature of these, many have 160 or 180 degree stats. It should have a 195.
Intake manifold gaskets can leak, showing up as a vacuum leak for the upper intake or oil/coolant leak typically down the rear of the block if it's the lower intake. Neither are that hard to replace.
Vortecs use the 'spider' injection with a central electronic fuel distributor. Strange running issues can often be traced to the hard lines cracking and leaking into the manifold or injectors that are sticking somewhat. Replacements are available.
Bolt pattern is the same as every other 4x4 6 lug chevy, so takeoff wheels from a newer truck are readily available and can significantly improve the aesthetics of the truck.
Here's mine with 2010 Yukon wheels:
I think they're great trucks. Definitely more truck-y than the modern stuff, but they are built well and can last forever. Many consider the GMT400s like this to be the high point of GM trucks, since the next generation more rust and electronic issues and further generations move away from being truck-like more and more.
