As an owner of a Ram 3500, SRW, 6.4 gasser, with 3.73 gears, and 6 speed auto, the only thing I’d consider changing is the gear ratio to 4.10. The 3.73 is just not deep enough when empty and driving over rolling hills as it causes the transmission to down shift frequently, rather than lug up the hills. Now when the camper is on, I just put the Trans in 4th gear and leave it there, and seems to do really well with minimal down shifts except in the mountains. Engine RPM runs between 2200-3000 depending on speed. Now for the gas vs diesel debate dollar for dollar it is impossible to make the diesel ink out on paper when you consider price of engine, cost of servicing, gas vs diesel fuel cost difference, etc. The gasoline engine in my opinion, for truck camper applications, wins every time if for no other reason than the added cargo capacity, and cost savings. Now the Ford vs Ram debate, I actually got to look at a F350 SRW crew cab with the 7.3 gasser and looked at the door sticker and was actually a bit shocked at the cargo capacity as it was 4120 lbs; my 3500 is rated for 4069 lbs I thought that all aluminum body would put cargo capacity a little higher. As for the 7.3, if you want it get it! It is old school cam in block overhead valve, injectors in intake technology. The engine bay has good lay out, spark plugs easy to get too on drivers side, and not terribly bad on passenger side. I think the Ford 7.3 gasser is gonna sell like hot cakes! Lastly, Go check out The Fast Lane Truck YouTube channel as they have bought a F250 with the 7.3 motor and are putting it through its paces. these guys pull no punches and tell it like it is.