So I'm needing another truck since my dad has taken over mine.    

It would be used regularly to haul wood, haul the family, haul lots of stuff, and be driven 200 mile round trips regularly, but I'm wanting a Chevy 2500 HD.   I have a Suburban 2500 and have been very impressed, so I figure this is as close as you can get in a truck.  (I wouldn't mind a F250 either)

Looking for a 6 seater, 4x4, 4 door.  Budget is 5-20K, but the only used trucks I can find in that price range are around 2004-2008 generally with a lot of miles.    

Did find a nice one locally for 16K that has 101K miles, but it is a 2004.  

Question is for you experienced truck guys  (subjective assessment aside, as in I'm not going to know exactly how the truck was cared for other than what the owner says, or Carfax says) - is there a point in your mind when you think a truck is too old or has too many miles to be driven distances regularly?  

And, can anyone recommend a good forum for full size Chevy trucks?  (what is the ARFCOM of full size trucks)  

Best to buy trucks 10 to 15 years old, they've stopped depreciating and are still new enough not to have major problems.

With GM the older you go the cheaper and easier they get to upkeep

The real question is how carlike do you want your truck to drive

For what it's worth, I'd drive my 14 year old, 333,000 mile truck anywhere, any time. It's an '01 Dodge Cummins. I drive it daily as well, as it's my only registered/insured vehicle at the moment. I also tow with it when the need arises. After repairing a few major things that the previous owner let slide (replaced rear end, replaced injection pump, and rebuilt front suspension), I've only had to repair or replace a few minor, expected things here and there. Very reliable truck.

That is b/c its a diesel?  Would a gas engine get that many miles?

If his truck was a person he would be in his mid to late 30's. Gas pickups are nearing the end around 350k, that being said my 89 Yota is still running strong 240k in. Daily driver/work truck.  

Nice simile, but if I was to put a human age on the engine in that truck (and the engine alone), I'd call it a toddler. It starts and runs as if it was just made yesterday. The only issue (if you want to call it that) that I'm having with it is that it leaks a little oil. I haven't even bothered trying to fix it.

http://www.gm-trucks.com/forums/
http://www.fullsizechevy.com/forum/forum.php
http://gmfullsize.com/
http://www.dieselplace.com/
http://www.duramaxforum.com/forum/

Sounds like a nice truck.  I've never had a diesel, but they sound more expensive to maintain.  I don't need the extra power, but if they are more reliable, it might be worth it.  I just don't know enough about them.

Yes ,They will go that far , my big block has 260,000 miles

All I can say is be careful. I bought a low mileage (27k) 2003 2 years ago. It has the dry rot, all the rubber underneath is toast. Lower ballpoint boots dried out, now I need balljoints, I need to take the bed off and replace the filler hose as its rotten, all the rubber in the brakes is toast etc etc. Once i get all that stuff replaced it "should" be gtg. Just not expected with such low mileage.

2 years ago I bought a 2005 Ford F-150 FX4 with 70k miles on it. It has 95k miles on it now and so far I've only had to replace the fuel pump and brakes. The current edition of this truck sells for $55k, I bought this for $14k. I drive it every day and took it to Wyoming last year for a hunt with 0 problems.

I have a 1997 Tahoe with a 5.7 with 190k that I would drive anywhere.  It's all about how well they're maintained, not the year or the mileage.

Thank you. They are indeed more expensive when it comes to buying diesel specific parts. That said, any time I need anything engine related (so far this has only been a thermostat, intake horn gaskets, and an upper radiator hose clamp), I go to the local Freightliner dealership instead of Dodge. Dodge dealership prices are unbelievable. I come out way ahead going to Freightliner. I do 5,000 mile oil changes and other fluids as needed. Here's the truck and the current odometer reading:

88-98 GM truck wtih a 350

This. I buy trucks with the assumption that they'll last 200k miles. I put 220k on my last one before I traded it on this one. Just pay real close attention to detail when you're checking out an older truck, but if it's been properly cared for it should be good to go. Be aware though that people will dump otherwise good older vehicles when they are on the verge of having major problems.