As I'm looking, seems that there are way more diesels than gassers. May have to go with diesel. Anyone know how much of a hit you take on payload going diesel over gas? Can't be too much.
I've got a 3500 SRW Cummins 3500, the payload is pushing 4,000 pounds.
I've read the thread and my take is to get the diesel. The exhaust brake alone is worth it when towing heavy and if you are towing in the mountains or foothills, the exhaust brake will be most appreciated. If you frequent the RV forums, the general opinion is once you start pulling north of 12K, it is time for diesel power.
I'm towing a Montana 3790RD, it is a 40-footer with a pin weight of 3,200 pounds and a tow weight of 16,000 pounds. I've read Billet Bee's comment about his fuel mileage and all I can say is the diesel in South Dakota must have a very low cetane rating to get that poor mileage. Towing my fifth wheel I average out to 13 MPG at 65 MPH, the MPG increases when pulling at 55 MPH. I have the standard output Cummins with 3:43 axle ratios and the 68RFE transmission.
My 3500 is a MY 2015 and the only issue I had with it is the rear air leveling system pump went out. When I bought the truck I also purchased an 8-year MAXCare service contract which covered the cost of the pump. If these issues are a concern to you, investigate the Mopar MAXcare service contract.
I was you in 2015, investigating a diesel-powered tow vehicle. If I took to heart everything I read I would not have bought anything, I'd be moving the RV by horse. Then it dawned on me, wait, all I'm reading are opinions, many from folks that do not or never owned a diesel pickup. They were simply repeating, with a twist, what they read somewhere else.
My wife and I spent a summer visiting campgrounds and talking with folks about campers and tow vehicles. The takeaway was simple, you won't be happy pulling heavy with a gas engine. I also noticed the majority of tow vehicles we saw at the campgrounds (in Michigan) were RAM Cummins, followed by Duramax and a few Powerstrokes. Back then, many Ford and GM owners were licking the wounds from the CP4 high-pressure fuel pump used on the Duramax and Powerstroke. The fuel pump had internal destruction sending small fragments down the fuel rails and into the injectors causing 10 to 13 thousand dollars in damages. GM covered the issue under warranty, Ford blamed the owners.
The only way to know for sure isn't possible because we don't know two things, how many RAM Cummins are sold versus the warranty claims related to the Cummins and its components. Like I said, I've had zero issues and I'm starting my 9th year of pulling heavy.