Help me price a low mileage Duramax

With the recent passing of my friend's father, his mom is finally looking to sell his long-unused Silverado 2500HD and I, as the resident car guy friend, have offered to help wherever possible. That's gonna start with pinning a value on the thing, which I'm having a bit of trouble with.

The truck is, I think, an 03 or 04, extended cab, Duramax, Allison trans, has around 85,000 miles, and I believe is the mid trim level (LS?) that they have owned since new. It spent the first few years of its life doing the rough work of a contractor's truck until his dad got out of that business due to health and financial reasons around '08-09 or so, was then driven lightly as his personal vehicle for a couple years after that, and barely driven at all for the last 5+ years after he lost his vision.

The interior is a bit grungy and definitely needs a thorough cleaning, but I think is otherwise in decent shape. Same goes for the exterior, decent paint, not beat up, cab corners and rockers are solid, just needs a good washing and waxing. It does feature some "deluxe redneck accouterments," such as horribly faded camo vinyl wrap below the trim line around the truck, chrome brush bar and tail light guards, a chrome ladder rack, and a toolbox in the bed. The vinyl needs to and will be removed before marketing the truck because it looks terrible. I'm not sure whether the rest of the accessories would help or hurt the value (maybe depends on the buyer.)

My buddy and his mom are said to have checked the blue book value at something like $18-20k about a year ago. That seemed high to me, and I came up with a value of $14,xxx on KBB's website last night. $14-16k was my original guesstimate and is still about the range that I'm thinking. I prompted them yesterday that a diesel that has been sitting like this one is not always seen as a positive, and a buyer is likely going to expect to have to spend some money on deferred maintenance. At the same time, how many diesels do you ever see with <100k miles?

So how much would you pay for this truck?

Year will make a big difference. Not sure when the LB7/LLY transition happened for Chevy. My GMC is an LLY and it's an '05. LLY fuel injectors are not under the valve cover as with the earlier LB7, and the LLY got a variable geometry turbo. 4WD?

I'd put a new fuel filter on it before driving it after sitting that long. It's not that hard to do.

Injectors are $200 each, and a known problem spot for common rail diesels, especially early Duramax. They run at up to 20,000 PSI. Documentation they've been replaced would help.

That said, my 2500HD is still going strong at 205k on the original...well...everything in the drivetrain.

Edit: Mine is a crew cab 4WD SLE (same as Chevy LS) and I paid $18k at a dealership with 160k miles about 3 years ago. It was and still is in very clean condition.

In reply to Tyler H:

Yes it is 4wd, forgot to mention that. Sounds like I'll definitely have to pin down the year, or maybe even have to read the door sticker since it seems to be a mid year switch, to figure out which engine it is and get a better estimate on value. A coworker, who incidentally may be interested in the truck, was also going off on the LB7/LLY differences this morning.

I might look into doing the fuel filter, but doing the injectors prior to sale is almost certainly out. I know she doesn't want to put any more money into the truck and I unfortunately don't really have much time to volunteer for maintenance at the moment. I can't imagine that sitting like this truck has will have done the injectors any favors though.

AIUI, the problem with the LB7 injectors is that they crack and start leaking fuel. I don't think this is caused by sitting around, just from use. One of the first symptoms is that after idling for a while it will blow big clouds of smoke when it starts going again, but it's a progressive failure and the truck will go a long way before it becomes a serious problem. If it's not blowing smoke or filling the crankcase with diesel, there's no reason to replace it at this point. If you're doing an oil change, you might consider sending a sample off for analysis (I like Blackstone) to see how it looks.

I paid $15K for my '02 LB7 6 years ago (crew cab, 2WD) with 125K on it, so while high teens is probably optimistic, it's not totally unreasonable if everything is in good condition.

If it's been sitting for a few years it may well want new batteries (it has two). They really need to be replaced in pairs, not one at a time.

I sold my '04.5 lly quad cab for 16.8k with 149k on it in one day with 2 backups waiting for call backs.

If it's rust free it will move immediately in the northeast.

The problem with the LB7 injectors is that they leak diesel into the crankcase....dieselbros call it 'making oil.' At 20000 psi, a little water causes a big problems. There is a water sensor on the bottom of the fuel filter, but it fails to false negative.

If you really want to know, drive it for a few days and find someone with efi live to check the balance rate on the injectors