I need help buying a Cummins.

If you go by cost to repair or upgrade, here are a couple things on these trucks to think over.

The 1996 - 1998 12 valves are great trucks - performance injectors are fairly cheap and the P7100 injection pump is one of the best pumps ever made for output and upgrade but can be VERY pricey to do so.

The 1998.5 - 2002 24 valves are also great trucks, BUT YES, some of them got crappy engine blocks cast in Brazil so it is worth getting down underneath with a flashlight to check stamps. You can get a full set of performance injectors for these trucks for under $500! Watch out for the VP44 injection pump though - run it with a low pressure warning light or they WILL get hot and burn out quick (terrible design with the electronics mounted right on the pump and the only cooling coming from the fuel - no fuel, no cooling) - a little over $1k to change it out.

2003 - 2007 true common rail is where the injectors start to get pricey. For a good brand name injector it is around $250 per injector... stock - and they only go up from there. The CP3 injection pump on the other hand is a great pump and much cheaper to replace than the earlier trucks. So many options for aftermarket upgrades on these trucks - tuners, intake, exhaust, injectors. It's ridiculous.

All those trucks had fairly poor steel bodies and some years the paint was even worse. You can overlook peeling clear coat/paint but truck rot on most all of these needs to be looked out for.

Which ever truck you end up with, my best recommendation would be to look into a FASS or AirDog fuel kit and use a lubricity additive with your fuel. Almost all the fuel now is low sulfur and these older trucks need some lubricity to last like they had been.

Now, if you get to a dealership and they say you are asking to little for the Dodge they have BUT they a have a nice Ford 6.0L you could have, kick them in the junk and run the other direction... If they have a 99 to 2000 Ford 7.3L though, maybe consider it. One of the most reliable trucks on the road IMO.