Just on the weight of the vehicle, the mpg is going to change between 1500, 2500, and 3500. Probably about 6-8 mpg difference between 1500 and 3500. About 5,000 lbs for a 1500, 7,000 lbs for a 2500, and 10,000 or 11,000 lbs. for the 3500.
The curb weight between equally equipped 2500's and 3500's it going to be pretty minor. Few hundred pounds at the very most. In the case of my 22 2500, it is 50lbs lighter than the same truck in a 3500.
The diesel will cost you more. Several thousand more to buy, it gets better mileage but the cost of diesel will more than cancel that.
The Cummins is an expensive option. But in my experience with diesel and gas hd trucks over the years, come sale/trade in time, that diesel motor (Ford, GM or Ram) will return very close to 100% of it's original sale price. That option holds its value better than rest of the truck, by far. To confirm, run the numbers on gas vs diesel in some older Ram's on KBB type sites. And remember to factor in the price of the diesel option in the year you are checking on, not current option price, as that goes up over time.
As far as mpg cost, with current pricing in my area, with diesel being less than 10% higher than regular, I'm way ahead of a gas motor in that cost. When diesel was $1 or more a gallon than regular, it was closer to break even.
For the first 150,000 miles, the gasoline is more capable. It will accelerate faster and pull the same weight.
I disagree. The diesel is always more capable when it comes to towing. In a 2500, because of the government mandated 10K cap, the gas truck is rated for more GVWR (because the motor is lighter), but the Cummins is rated to haul more weight. For bigger loads and big hills/mountains, the diesel will out pull it with ease. Torque is what pulls trailers and the Cummins has about twice the torque the Hemi does.
As far as acceleration, I have no idea and don't care. I don't buy an HD truck for that reason. The Cummins has no problem getting up to speed, with or without a trailer.
The diesel will make more noise. I'm one of those strange folk who would cancel the sound of my v8 if I could. I don't want the sound of the v8 or a lawnmower engine in some SUVs.
I don't hear the diesel in my Ltd Longhorn while in the truck. I believe there is some noise cancelling tech at work. But even standing outside, it is FAR quieter than the diesel motors of old. And no more diesel stink or smoke. Diesels have come a long ways.
Except for leftover mores created by the comparison between diesel and gasoline engines in the 1950s-1980s there is just not much justification for buying a diesel pickup truck.
Maybe not for you. They make perfect sense for a lot of folks though. Heck, you can't even order a 2500 Ltd or Ltd Longhorn anymore with the gas motor. Ram killed it off for lack for sales.
I'll get disagreement on this, but look at the profiles of the posters. If they have a picture, how old are they? Perhaps grew up 1950s-1980s. I'm 77 myself and I have heard just about any comparison that can be made. The bottom line you'll spend, by my estimation, which is just that, an estimation, it'll cost $1.00 per mile more for the diesel than gasoline at least for the first 4-5 years. And if you keep it longer it'll never recoup that amount.
Please show us your math here. The only way you could be close to that is if you are treating the cost of the diesel option as a total loss. As I said above, that is far from the truth. If you keep a truck until it's junk, you will have reaped the benefit of better mileage all of its life and the far better towing experience.
A 2500 over a 1500 has marginal reasons to buy, similarily equipped there is not much difference between towing. Don't scream at me there, look it up.
I think you need to look it up. A 2500 is rated to pull far more weight.
A 3500 needs a valid and continued use to justify. I can't think of nor have I heard of a valid reason to put a diesel in a 1500 or 2500. it might be useful in a 3500. it will cost a good deal more.
And it will net a good deal more at trade/sale. Again, I've owned both. Pulling trailers through our Ozark Mts or my trips to the Rocky Mts each year will show in a dramatic way why diesels can make a lot of sense in 2500's. The difference is literally night and day, for both going up and coming down grades.
And some of the baby diesels in 1/2 ton's get a lot of love. The baby Duramax can get above 30mpg and still pull a good load. Seems like a worthy option to me.
Parking a trailer in a fancy park or posting on this forum it will be nice to brag about the truck you have, but I'm not paying money to brag.
Nothing wrong with going gas, or whatever you want. But much of what you are saying above is just plain wrong in many cases.