O.T. New(er) truck? What to get?

I want to go 3/4 ton this time. After owning an extended cab, I don't know if I want another one. Would rather have a crew cab (Would be easier with future kids). However, the crew cabs are much more money than the extended. I also would like to have the Duramax. Better mileage than the 6.0 litre. Better power. Better transmission. Also. MORE MONEY. I am thinking that my next truck will be kept for a long time. Longevity is an issue. Reason being is because I am going to be 22 soon. Probably married by 25 or so. And kids coming by 30. Truck will probably stay with me through most if not all of this. I have the luxury of working for a truck accessory company, so finding all the goodies to deck it out will be easy, and pretty cost effective. My question is, I guess. What will be the best bang for my buck? 2003-2006? GM 2500 HD crew cab or ext. cab 6.0 gas or duramax diesel. I currently have for towing: Snowmobiles, boat, a '41 Case SC, and hopefully will once again have a Farmall M.... Which I did pull with my half ton. Twice. Maybe even some green? Unstyled JD A. I will also be using this as a daily driver to and from work. I only live 2 miles from the shop, so in town mileage is not what I am concerned with. Highway and towing are the big factors. My budget is probably right at 20 thousand. trucks seem to be in the 15-25000$ range for gas vs. diesel, extended vs. crew cab. Anyone have any thoughts?

Diesel has the highest BTU content and power of the popular motor fuels (propane is the lowest)and consequently the better mileage no matter what your manufacture's choice is. (Personally I am a Dodge man and have had excellent luck with Dodge trucks over about 45 years of vehicle ownership).For durability and reliability I believe the Cummins engine has it hands down. That said, diesels take more care and maintenance than gas engines but you should never have to lift the heads on a Cummins engine for at least 300,000 miles. Ask the over the road truckers and hot shot drivers. Like is stated below, there's a reason you see more Dodge and Ford diesels trucks pulling commercial loads than Chevy or GMC. Take a look at he engines in Peterbuilt, Mack, International Freightliner, etc. They are usually Cummins or Cat.

For your needs I would think the largest V8 gas engine would pull what you want and give the most optimum fuel economy for less the initial outlay. You aren't putting enough miles on the truck a year to justify the cost of a diesel no matter what brand. If its pulling power you want go to a low gear rear end and a gear splitter to let you run in "overdrive" when unloaded. There are several brands of these on the market and have probaly been perfected by now. This gives you the equivalent of a two speed axle in a pick up package.

http://www.ford-trucks.com/forums/forum31/