So I own an 89 F250 with a 5.8, a 99 F250 Sd with 6.8, and used to own a 2010 F250 with the 6.4 turd diesel so I thought I’d share my thoughts too.
The 2010 had the best performance across the board but there was a huge downside to me...when I popped the hood I needed an engineering degree, a third elbow, and fingers that worked backwards to work on anything lol. No room unless you remove half of the parts to get to stuff. Plus, the regen sucked. But it rode like a Cadillac compared to my others and fit 35” tall tires on stock rims. Only averaged 14mpg unloaded with a camper shell. The reason I got rid of it was because the stupid engine decided to suck the oil of the oil pan via a bad turbo seal at only 67k miles and ended up grenading on me. Newer tech is awesome until it needs to be fixed and then it’s $$$ and difficult. Final thought. Rode awesome but to me it was too complicated and expensive to work on and modify with too many things that could and did go wrong.
The 99 with the 6.8 is thirsty for her fossil fuels. Gets about 11mpg unloaded and doesn’t ride terrible, but it’s as good as it’ll get with a leaf sprung solid axle front. It’s reliable as anything I’ve owned and just crossed 230k miles last week. I got it at 63k miles and the only issues I’ve had other than regular maintenance and wear and tear parts is it spit out two spark plugs from the head (an issue with Ford only putting 4 stupid threads in aluminum heads on triton engines from 99-02). Good low end torque and acceptable ride. If you go for this engine, look for newer than 2003.
Great truck, reliable, easier to work on, solid axle, some tech upgrades but not too much.
My favorite though is my 89 F250 ext cab longbed. Yes, it has the turn radius of a dump truck but my TTB front rides really nice. It’s ride is better than the 99 on and off road. Dual tanks factory mean more fuel capacity. With my soon upgrade to a 38 gallon rear tank, I’ll be able to carry 57 gallons on board(about 53 gallons usable). It’s the 5.8 with a c6 trans, and 4.10 gears on 33” tires. If I keep it at 55mph and under it normally sees 10 to 11mpg, any higher and you can watch the fuel gauge fall lol. It does have a tall camper shell which may or may not affect the mpgs. It’s the one I’ve chosen to build as a dedicated overland truck for one simple reason... ease to work on. Minimal electronics and mostly mechanical operation and so much room to work on stuff. If you’re looking at obs fords, look older than 92. As others have pointed out, the tech didn’t change much in those years and 87 to 91 got the best of both worlds in my opinion and the prices are much better. I found mine for $2500 with 47k original and documented miles. Since I waterproofed the eec, I’d have no fear of fording and causing issues with the lights, trans, hvac or anything else other than the radio. Yes, you’ll have to do upgrades like putting the headlights on relays, and wear and tear parts will need to be replaced, but the lower initial cost makes that much easier. I look at it like this, if I spend 15k building it the way I want, I’ll be ahead since I can’t find anything worthwhile 99 and newer for under 15k or any decent obs in this trucks condition for less than 8k. Plus, the 302/351 (5.0/5.8) Ford small block v8 is very easy to find parts for anywhere in North America and much of South America and Australia.
Simple, reliable, can go through hell and get you back, easy to work on and repair in the field, lower initial investment
Anyways, just my two cents. I wish it was the old 6.9 diesel but other than that, my old brick is perfect for me. Just gotta watch out for tight switchbacks lol.