sweet, i just did the 'shopped for n bought an older diesel' thing.
most work I ever put into buying a used vehicle...
pound the pavement, look at a BUNCH of them, and then buy the one that you really really like. I think it was 27 trucks that i took the time to physically look at, i only bothered to drive like 3 as the vast majority of them i lost interest in pretty quick.
As far as trucks go, i'm definitely a ford guy, but in my shopping i didn't limit myself. i checked out every dodge ford and gm i could in my price range.
not many gm's... most were way way older and in horrible shape, or very new and $$$$. I only checked out one and it would have been a contender if the seller dropped a couple of bucks, but he didn't.
plenty of dodges, i have a lot of confidence in the motor and all of them i checked out ran well. but the rest of it... i had trouble finding ones that were overall in good condition. some of them were pretty riced out, and some were ragged. i think all of the dodge stuff just falls apart around the cummins stuff.
tons 6.0 fords. i stopped looking at 6.0's though. even though there were some nice trucks out there, at some good prices, i just couldn't handle it. i'm not a gambler and taking that on was just too stressful. snapping up a cheap larriot 6.0 for a fummins swap would be spiffy though.
plenty of 7.3's. they spanned the spectrum though. some were in pristine condition, others not so much, but overall the trucks in general hold up well. I can't think of much that i would consider a 'gotcha' to watch out for, but i could expand on general advice if it helps.
through the course of my shopping, i decided to begin ignoring millage and focusing on how well cared for the vehicle was. a 7.3 or a 6bt can go a bazzilion miles assuming its owner loves it and takes care of it, so i focused on this aspect. if one of these is well loved, a 200,000 mile truck looks like it has 40,000 and a not loved truck with 120,000 looks like it has 500,000.
i would also keep some transmission money in your pocket. dodge or ford, they all appear to be about ready for some trans work, or you pay a premium for one just done. if you can find a stick shift, this is a recipe for reliability, but even still you should consider a clutch swap sooner than later. these clutchs don't really wear out, but can fail in catastrophic fashion and take out the trans at the same time. i just ordered a south bend for mine.
in general, be prepared to take it home and spend some time and money. after getting mine home i spent several weeks going through and doing ALL of the general maintenance items, fixing a bunch of little things and have set money aside and made a plan to do some of the bigger things that make sense. (clutch and up-pipes are top of my list)
on the topic of "chips" and other performance mods...
why not buy one that already has a chip and other performance mods? if you like the truck and might like that sort of thing, why not save yourself the money and buy one that already has that stuff? again... its all about how well cared for it was. i looked at some that were modded and chipped, and obviously BEAT ON. so i passed on those...
the one that i ended up buying has a ton of performance upgrades, lots of cool stuff that i wouldn't be able to afford right now. so it was a bonus for me.
best of luck in the shopping! it can be a pain but its worth it to be picky. i loooooove mine. i've always been a big fan of turbochargers and have owned some powerful turbo cars, but i've never had something so insanely powerful while also so efficient and reliable.
one thing to definitely watch out for is emissions. assuming you live in the metro area, it will have to pass "diesel emissions". essential its a visual inspection that it has all manufacturer installed emissions equipment and a loaded dyno test that checks exhaust opacity. this is not something to overall stress about, even a truck that makes a fair bit of smoke will pass, but it needs to be in sounds running condition and you need to be able to remove the chip if it has one or set the tuner back to 'stock' mode.
a seller is legally required to provide you with a passed emissions test, even if they live outside of the emissions required area's. but, NOBODY is going to do that!!! its just not gunna happen. they'll sell the truck to somebody else if you push the issue. i purchased mine form a guy in Avon (no emissions), then i had to install a catalytic myself (purchased with a 4" exhaust, no muffler, no cat) and take it up for the test myself.
Tim M Hovey
1950 cj3a: FJ60 Axles, brakes, and steering, Willy's
sheetmetal and a Buick engine, held together with
metal from the scrap yard glued together in a garage in
Louisville and dragged around behind a F350 Diesel.