Going to look at a 98' GMC ext cab tomorrow and just wanted to get a list of things to check for. I own a 97 GMC that needs work so I know of a few things. New truck has 195k on it and comes with a Fisher Plow. Also whats a good price range? Guy wants $3500 and is pretty firm. It's in great shape, but not quite perfect. Few dents and needs a near rear bumper soon. But it does have a new Maine State Inspection sticker.

 

With the engine cold start it and check for smoke out the tail pipe. Take it for a test drive. How well does it accellerate and shift thru the gears and down shift. How does it steer. You have yours to compare. If it's a 4x4 go to an empty parking lot and turn it both directions while in 4 wheel drive and listen for any noises (CV joints will click if bad). Hows the brakes. $3500 is not a bad price for a 15 year old truck. Look it over real good for oil leaks etc. The mileage is no big deal as vehicles for the last 20+ years are doing good.

 

Really everything TMW said. If it comes with a plow, test its features like the controls inside the cab, if it's easy to mount up, if all the directions work and if the lights work on it. Check for coolant leaks on the corners of the intake, look underneath it and look for oil leaks, check the oil cooler lines for repairs that might not hold, check that the 4x4 works good, make sure the steering isn't too loose, the brakes shouldn't have lots of travel before they start working. General type stuff.

Cab corners and wheel well edges LOVE to rust out, so carefully feel around those areas for rust bubbles or signs of repairs. Check the bed for the part by the cab to be all smashed in indicating it being abused or used as a work truck.

 

To me the most important test takes someone riding behind you. I watch the exhaust for when the engine is decelerating, like in between gears on a stick or going down hill. A puff of exhaust between shifts or a trail while going down hill with the engine braking the truck indicates bad rings. Smoke under acceleration might be cured, smoke during deceleration cannot.

 

Bring a rag or towel with you for checking the fluid. I like to pull the oil and trans dip sticks and check their color and smell. Any burnt smells could indicate trouble, especially with the trans. If color is good for both, it could indicate better care being given in regards to general maintenance.

I also visually inspect brake pad and rotor wear, any leaks on the ground, air filter cleanliness, and any fluids (oil or coolant) that are pooled around the intake manifold area. Afterward, I ask the owner about any existing problems and how frequently general maintenance was performed. Of course the ownder could lie, but if his claims do not match up with what I see (e.g. He claims brakes were replaced recently, yet I see extreme pad wear or grooved rotors. Or he claims that oil was changed regularly, yet the oil off the dipstick is black), I'll at least have a foundation to judge his honesty on. These checks are the best way to get an indication on the condition to the rest of the engine as you're going to get in this setting.

Beyond that, nothing is as good as a test drive. A cold start, steady idle, acceleration up to about 50, a good, safe braking action, and continued steady idle is good news to me.

Have the owner work all the lights. Turn signals, brakes, running lights, head lights, and hazards. This is an additional check on regular maintenance on the car and is also important if you purchase it, as the vehicle will need to be road-worthy if you take it home.

Lastly, just look for anything out of the ordinary. Cracks or tool marks around the gauge cluster or any where else. Repaired electrical wires, hoses, or anything that you know is wrong with what you see. Sometimes stuff happens, but on occaision a question may make the owner slip about something serious.

Oh, and make sure it is HIS name on the title, and how many previous title owners there were. While it is not gaurunteed, a large number of previous owners can sometimes mean something is or was wrong with the truck.

 

A lot of great tips above from our members, all I have to ad is... seeing as it is an older plow truck. Crawl under the truck between the back of the cab and the front of the box and inspect the frame on both sided.
This is where a plow truck will fail if the driver continually runs hard into snow banks.