Used diesel buying question

The short answer is $25K-$35K. My 08 is book at $23K but I would not sale it for $30K. A new truck is to expensive and a used replacement is got giving me anything I do not already have. It still looks good, has all the power, speed, comfort, and features I want or need and is paid for.

Good luck and for what you say you want it for you may consider a V10 Ford instead. They are more plentiful and cheaper without being less capable for your stated use.

BTW make sure what ever you get has a limited slip or locking rear end.

I'm pulling a travel trailer now that, ready to go, is about 6500-ish. The Suburban can do it, in the short run. But, it's really working hard. I'd keep my trailer for sure as we think it's perfect for what we do. I have been pulling travel trailers on and off for a number of years and always with gassers. None of them have ever been really great at it. I keep hearing about how great diesels are for towing. My guess is that for 6500 LBS of trailer it would be pretty awesome. At the same time, I use my Suburban as a daily driver and I'd need a truck to get me back and forth 95% of the time. I like the 4x4 option as I occasionally need it. The Suburban has been reliable so far. The 5.3 is decent on gas but, really pretty close to maxed out at times when towing the trailer. I have read that the 6.0 GM V8 is a modest improvement. I don't want to commute with an 8.1 2500 Suburban gasser. The diesel seems like a good option.

Don't get me wrong the 7.3 and 5.9 are decent vehicles. However at this point technology has passed them by.
The 6 speed transmissions and stronger frames and suspensions of today make it hard to recommend a 15 year old diesel truck over a more modern gasser.
06/07 Could be your GM starting era. 2011 6.7 for Ford.
I'd skip the 2008-2010 DPF era trucks as well.
Not familiar enough with Dodge to know there qualifying era. The fact they are no longer trading/selling as Dodge speaks for itself.

Something like the Ford 7.3L has a "legendary" reputation due to the International T444e engine.

But they are aging. The maintenance schedules and troubleshooting is quite well documented and known.

If you keep up with the maintenance, they can easily go 400k-600k of well serviceable miles.

If you are looking at these 1999.5-2003 models, it is best if you are comfortable with doing your own maintenance or know someone who can help you out. It would be easy to go broke looking at dealers to do all the work for you, LOL.

This site is friendly and helpful for Ford 7.3L : FTE 7.3L Diesels 1999-2003

“Good used diesel” is a pretty broad brush. I’ll say between $10k -$60k.
$10k being for a nice used 1st Gen Dodge Cummins and $60 being For last years super Lariat, Laramie low mile loaded crew cab.

What years are you looking at?
Payloads increased in 2011 which I imagine is a good place to start.
Without doing any real research
$20-$25 grand would be my starting budget number.

The only cost difference is oil and filter changes. 10 quarts vs 5 or 6 for a gasser. My fuel filter is around 75 dollars depending on where I buy them. Diesels definitely will cost more IF you have to do any major repairs. Every thing else is a wash.

You don't say what your plans are for the truck, but if you plan on towing a fifth wheel, forget the 3/4-ton trucks and go straight to at least a single rear wheel 1-ton. A diesel 3/4-ton will pull anything but you will hit the limit for the rear axle with trailer pin weight very quickly. The costs differences are minimal. (The same probably applies to use with a truck camper, too.)

All three US brands make good trucks. If you're talking Ford Powerstroke, the 7.3 was a good, solid engine - it's the 6.0 and 6.4 you want to avoid if possible. With the new 6.7, Ford got it right again. Cummins has never made a "bad" diesel motor in my opinion and the GM Duramax, after a few pressure rail problems the first year or two, is one of my favorites, as well. The newer the truck, the more speeds you're going to get in the transmission. The more speeds, the closer the gear ratios and the better the performance with heavy loads.

For a good while, Dodge/Ram had a reputation for body rusting - especially around the wheel wells and rocker panels. That's probably not an issue any more, but check any used truck thoroughly if you're considering purchasing it. In the southeast, you won't have as much problem with salted roads as they do up in New England or the upper Midwest.

An oil change for a diesel is more expensive than for gas - but the diesel trucks go longer between oil changes than a gasser, so it's probably a wash. With current diesel prices what they are, I'm actually paying less for fuel since the diesel truck gets considerably better mileage that would a gasser pulling the same load. Repairs, however, are a different story. They are quite a bit more expensive than for a gasoline engine. On the other hand, diesel motors tend to be more reliable and run for more miles.

Finally, there is the issue of finding a "good" used diesel truck - especially in a work truck trim. These units tend to be purchased originally by companies or individuals who use them for business and you may come across many that have been treated like "it's not my truck." Don't limit your search to your local area (maybe look in the Carolinas, Georgia, Tennessee, etc.) and, if/when you find one you like, have a qualified diesel mechanic go over it thoroughly before making a decision.

Rob