Replacement Engines?

I'm a supporter of staying out of debt and making a truck work for you. So my comments next will not support the previous statement but I really think you need to look at a 3/4 ton gas job if anything. After reading the comments again and all are really trying to help you, I think I would just bite the bulet and upgrade. So here's my story: I had a 2000 Chevy 1500 with 5.3 and 3.42 gears. Was pulling a 6500 lb fifth wheel and it did ok. I pulled around Florida and Goergia with occasional NC. I had the truck paid for and upgrading was just not my deal. But we needed a slightly larger fifth wheel cause my daughter was born. My aunt had a 26-28 footer that fit that bill nicely and within our budget so we sold ours and purchased hers. Wieght was around 7600 dry so wet was over 8k easy. Well after looking at the gear upgrade, suspension upgrade, tire upgrade, programmer upgrade, transmission clutch pack upgrade, and. cooler upgrades, ect.... I realized that I just needed to go to a heavier truck that had it all from the get go. That's why a lot of people on here advise to just upgrade to a larger truck. We all have been there and done that. The cost of adding to a truck to make it what you want may not be always the wisest financal decision, when a larger truck can be purchased used with good service. I'm not by any means knocking 1/2 ton trucks at all... That's not my point and won't be, just my thoughts and experiences. I have a gas 3/4 ton now, handles the loads oh so easy. There's so much more then just an simple engine upgrade at stake. I just think that a simple gas or if you feel diesel 3/4 ton would work much better for you in the long run. Diesel not needed for the wieght that your pulling for sure... Gas would be more then good for that wieght. I'm trying to give you my experience since I have been down the same road. I hate to poor money into a truck when I should have just bought the right one for the job to begin with. Hope this helps, Keep us updated and good luck, a lot of good people here trying to help u out for sure.