My 2 cents, OK I'll give you whole nickel...It depends so much on how much towing you will do, what the terrain is like and how much you are going to use the truck for other things. Do you want to ride around in a rough riding truck the other 90% of the time?
The first thing I would keep in mind is that "tow ratings" have nothing to do with how the vehicle will tow something other then the higher the better. Your typical truck salesperson will simply look at a chart and say.."yes you can tow that!!!" Tow ratings I sincerely believe are based on what weight you can put behind it and not void the warranty for abusing the vehicle for warranty repairs. It does not mean you can tow said trailer without some white knuckle towing adventures i.e. trailer jerking you around like you weigh nothing, scaring the xxxx out of you on a bridge, running at MAX "safe" temperature, and letting you drive with 10 cars behind you like baby ducks who will risk their lives, your lives and anyone elses life to pass your slow truck.
I have used a half ton truck to tow a 7500 lb trailer and tractor (never again), used a 3/4 Ton 460 Ford which towed wonderfully, but literally beat me to death if I wanted to go anywhere with it empty. (90% of the time). I settled on a happy medium, a 99 Chev 3/4 Ton extended cab w/454 Vortec V8. When Chev went to the Vortec engines in 96 it made a big difference in the engines. The best thing is that this truck rides rougher then a half ton but nothing like my Ford. I don't cringe at the thought of my bones being rattled apart if I want to go somewhere empty. Unfortunately the newer (2001) Chevy's ride rougher probably due to their now 15K tow rating? We don't use this truck much so the gas vs diesel debate is moot. It is low enough that you can actually reach over the sides and get stuff and get in it easily. I also plan on towing a 4210 with it shortly. Currently towing a 6400 Kubota TLB, trailer weighs about 2500. (10K trailer). The truck weighs about 5800 and gets jerked around now and then even with a weight distributing hitch and sway control. Still have some more experimenting to do at the weigh station with axle versus tongue weight though. If I want to control tractor even better I can strap on leaf spring helpers. At least I can take them off the rest of the time if I want. E rated tires on the truck seem to help if you want to keep sway at a minimum. I have also seen people towing with trailers whose tires are not rated for anywhere near what the trailer is hauling...
The gas versus diesel longevity debate is interesting as rebuilding engines seems to be a rather minimum cost these days compared to insurance and other repairs. I've seen some reman blocks pretty reasonably priced, even at the dealer. The thing that will knock you over from either vehicle are those little black boxes that cost $900 after you pay them $200 to tell you that you need one. The other thing to figure in is truck length, longer the wheelbase the better it seems to tow, and the worse it seems to park. I have a short box on mine and it is much easier to park then my old long bed extended cab ford. Up until I heard Chevy's current diesel I would never have bought a diesel as I can't get past that terrible knocking (which is how a diesel combusts the fuel). They were/are loud and obnoxious. Semi's don't sound that way, most tractors don't, but the pickups, geez. The new Chevys sound like my Kubota (quiet). I know, I know, I must be getting old!
