While diesel has always struggled to find a mainstream user base here in the US, Americans who drive diesel engines tend to swear by them. The low-end torque offered by diesel and the durability of these engines are big pluses, and, as gas prices continue to rise, diesel's superior fuel economy is more helpful than ever.If you're looking for a diesel-powered pickup that might well last you the rest of your life, your best bet is going to be a heavy-duty Ram with a Cummins under the hood. We reported a while back on a Ram 3500 with more than two million miles on the odometer, far outrunning the highest-mileage Toyota Tundra or Toyota Tacoma. Here's what makes the Cummins-powered Ram 2500 and 3500 pickups such troopers. A Cummins Ram Could Tow A Mountain DodgeThe 5.9 ISB Cummins-powered Heavy-Duty Ram 2500 (not to be confused with the earlier 5.9 6BT-powered 1989-1998 models) ran from 1998 until early 2007, with a 2006 model having a towing capacity of 13,600 lbs. The 3500 was available with dual rear wheels, and can tow up to 16,250 when properly equipped.Both trucks pack the exact same engine, with the difference in pulling power coming down to the suspension setup in each truck. Towing capacity actually peaks in the 3500 Rams. The 4500 and 5500 both sacrifice some pulling power for their heavier frames and suspension systems. A fully outfitted 5500 doesn't just tip the scales, it crushes them, weighing in at over 10,000 lbs. Cummins Rams Are Still Going Strong Ram The 2026 Heavy-Duty Ram pickup is available with a more powerful 6.7-liter Cummins diesel, another straight-six B series, like the 5.9 before it.For 2026, when properly equipped, the 2500 tops out at 20,000 lbs of towing capacity, with a maximum payload capacity of 3,930. The 3500 can tow up to 36,610 lbs, with a maximum payload capacity of 6,050 lbs. The 6.7 Cummins has been powering turbodiesel Rams since the 2007 model year. A 5.9 ISB Cummins Might Last Forever Bring A Trailer You really can't go wrong with any Cummins-powered Ram. Epictechwill, on the I Got A Cummins forum, reports clocking an incredible 1.3 million miles in a 2014 Ram 3500 with a 6.7 powerplant. That's probably more miles than you put on your last three cars combined. But it's nothing next to the 5.9-powered 2000 Ram 3500 belonging to RV deliverer Howard Clayton.Ram's partnership with Cummins dates back to the 1989 model year, when the Ram was made available with a 160-hp 5.9, cranking out 400 lb-ft of torque. Dodge had been struggling to sell Mitsubishi diesel-powered trucks to Americans, with limited success, and the Cummins turned out to be the missing piece of the puzzle.The B-series has been around since 1984, with the 5.9 engine using a cast iron block and head with a forged steel crankshaft with seven main bearings, and a forged aluminum intake manifold. The ISB is a multi-valve pushrod engine, packing four valves per cylinder, lending it the nickname "24-Valve" Cummins. The Dodge Ram made the jump to the ISB midway through the 1998 model year in order to keep up with emissions requirements. How To Reach One Million MIles Dodge We could tell you that the best way to reach a million miles in a Ram HD is to change your oil early, but that's not what Howard Clayton did. Something that almost all high-mileage trucks have in common is that their owners use them for long-haul delivery work. The bottom line is that highway miles are going to put a lot less wear and tear on a vehicle than stop-and-start city miles, so, as long as you're not using your Ram as a grocery-getter, you're halfway there.But, routine maintenance is important. RepairPal estimates that a 2006 Ram 2500 should cost you around $1,075 a year to maintain, with the following being the most expensive common fixes pertaining to the engine. Turbocharger oil line replacement $373 - $427 Oil pressure sensor replacement $299 - $322 Oil change $217 - $241 Engine leak inspection $122 - $179 Fuel filter replacement $135 - $168 We don't doubt that some degree of luck played a part in Howard Clayton's high mileage, so don't expect to away with skipping oil changes. What Will A 5.9 Cummins-Powered Ram Cost You In 2026? Dodge Taking a look at some current listings, via our own marketplace tools, here's what we turn up. A 234,959-mile 1999 2500 is selling for $14,595 in Florida. A 327,044-mile 2006 2500 is selling for $5,999 in New Jersey. An 85,944-mile 2005 2500 is selling for $8,495 in California. A 71,151-mile 2001 2500 is selling for $9,995 in Oregon. A 96,817-mile 2001 3500 is selling for $17,998 in Kentucky. A 113,386-mile 1999 3500 is selling for $22,495 in Connecticut. You can buy a high-mileage Ram for a song, but, even though these trucks have been seen to cross one million miles, 234,959 miles on the odometer means that you're taking a chance on what might have been 27 years of neglect and misuse. It's hard to recommend spending a five-figure sum on something with nearly a quarter million miles on the odometer when there are plenty of sub-100,000-mile models out there selling for modest money. It's Sort Of A Buyer's Market These trucks are high-value, but it's kind of a buyer's market. If you're retired, or you inherit an old pickup from your favorite uncle, or you're otherwise trying to get rid of a big, diesel-powered truck, then it's just a big noisy burden.Heavy-duty pickups don't make a lot of sense as daily drivers, and, if you don't have any use for a dedicated work truck, then this is just a three-ton yard ornament that's losing value every day you leave it sitting around collecting dust. So, the going price is pretty low, because the niche of potential buyers is pretty narrow.