Since you’re looking at Rams only, the 2500/3500 discussion can stop. You’ve already heard about the on paper capacities vs the real world capacities.
Looking used, good price for a good newer diesel is already a needle in a haystack. A 3500 is like a hay colored needle in a haystack.
Find the truck you like with the mileage condition options and price you can live with. Don’t obsess on whether there’s a 2 or a 3 on the door badge.
You mentioned older than 2014. Good choice for your use, save for emissions, IMO. Pre 2013 emissions on Rams is the old style dpf which gets considerably worse mileage and is more susceptible to problems. Not a deal breaker if you save $ or are willing to delete it. The early 4th Gen truck’s 2010 and up are the 3rd gen chassis from 2003 on.
Very capable and bugs worked out just not quite as heavy duty as the newer chassis
