Did I really need a 2500HD? No, I'll be honest, probably not (though towing my tractor/cars/equipment rentals is going to be more comfortable). But what I really did need, was a rust-free, low-mileage, dependable work truck.
I really wanted to find a chevy/gmc 1500 with a 6-spd transmission and cylinder-deactivation, but it turns out they are still out of my price range with anything less than a ton of miles.
A 1500 truck with the 5.3L V8, even with the old 4-spd 4L60 trans, would likely return appreciably better mpg than this, but I honestly could not find a rust-free, well cared for example in many months of searching.
I searched craigslist daily until this beauty popped up. A one-owner, 2500HD SLT, but in the smallest/lightest configuration (aside from the regular cab / long bed, which doesn't work for me as I have 1 kid now and another on the way) and with the smallest available engine, the teeny tiny 6.0L V8.
2003 GMC Sierra 2500HD SLT
LQ4 6.0L V8 engine
2WD/4-HI/4-LO manual transfer case
4L80 HD 4-spd Trans
4.10 rear end gearing (ugh)
~5600 lb curb weight (best data I can find)
10,200 lbs towing capacity (under-rated) and ~3800 lbs payload (dayumn).
Not a great starting point for economy. I somewhat naively assumed that with my laid-back commute of gentle back-road cruising, I could still see high teens in this truck. Now it would appear that will be difficult (but I WILL get there this coming summer, or die trying).
Starting fuel economy in the fall months: 13.0 mpg
Now that we're into real winter... it tried to get worse (a LOT worse) but my initial mods are holding it steady so far.