You're shopping two completely different trucks under one badge. The old compact Rangers (1990s-2011) earned their reputation the hard way, owners routinely push them past 300k miles on original drivetrains, fix them with junkyard parts for pocket change, and replace them with another Ranger when rust finally wins. The current midsize version (2019+) tows 7,500 pounds, rides like a car, and packs a punchy turbo four, but it's grown to F-150 dimensions at near-F-150 money, and 2021-2023 models are showing up with oil leaks and transmission hiccups while still under warranty. Buy a clean old one if you want a proven workhorse that'll outlast your career. Skip the new one unless you need modern towing and safety, and even then, you're betting on Ford ironing out first-generation kinks.
The Ram 3500 is a truck built around one of the best diesel engines ever made, wrapped in a body that can't quite match it. The Cummins 6.7L will run to half a million miles with religious maintenance, but electrical gremlins and corrosion show up embarrassingly early, one owner found corroded connectors at 2,500 miles. Spec the Aisin transmission and budget for DEF system upkeep, and this truck will haul 36,000 pounds until the sun burns out. Buy it if you need maximum capability and can wrench or afford a good independent diesel shop; walk if you expect Toyota-grade fit-and-finish or can't stomach chasing electrical faults.