Duramax upgrade ...

[Rooster]

I'm stuck in my own gas v. diesel decision. Towing a heavy azzed toy hauler this year has put a huge amount of strain on the 10 year old 6.0L (with 129k miles on it). I've spent over $2k alone in repairs/upgrades and still my towing capacity suffers as well as the mileage. Currently, when fully loaded, I get about 6.5-7mpg. Not bad, but one of my longest journeys for racing is about 350 miles, that can add up and it takes a toll on the drive train. So far, I've upgraded the exh manifolds to headers as well as opened up the exh a bit with high flow mufflers. The cats are stock units. I've also upgraded the plastic tank radiator to an all aluminum unit while replacing the water pump and belts. And in an effort to make it breath better, I've added a cold air intake. I have a few options that I'm looking into at the time, but really there is only one solid way to go is a diesel conversion. I'd like to see what you guys think, so I'll list them out, cheapest to most expensive:

1.) Engine management with tune on current setup. I think with a good tune, I could extract a few more hp/torq while also help with the mpg. This is the sub $1k option.

Pro's: Its an inexpensive way to extract a little more HP/Torq and that may be all I need

Con's: It wont be enough.

2.) LSA conversion with (or without) LS3 or LQ9 cam. This is pricey ($3k-$5k) but very doable with my current motor. The downside would be I'd need a better trans as the 4L65E would STB fairly quickly.

Pro's: It'll still need a tune after, but would be an inexpensive route to see if the power alone would help. Plus, no motor swap.

Con's: Putting a supercharger on a 10 year old motor could end up roasting the motor. Plus, it would most likely take out the trans at some point.

3.) Duramax conversion with allison trans. Pricey ($10k-$15k without drive train), but would solve all my issues. Plus I'd have the only duramax hummer in town.

Pro's: Over and done. It'll handle the towing and mileage would be awesome. Plus the cool factor.

Con's: It'll cost as much as the hummer is worth to put a duramax into it. Not a deal breaker as I love the bodystyle, Another caveat is, my frame. It's scaling pretty bad. Not sure if there is any rot,

but may need to be replaced.

4.) New (to me) truck. New Duramax GMC/Chev pickups are getting reasonably priced if you dont mind used. Currently found a 1 owner 2011 GMC that'll fit my needs for $23k. But I'd have to give up the hummer.

Pro's: Over and done as well. I can sell the H2, get a pick up with no financing.

Con's: Loose the H2, which, is a fantastic vehicle. Sellers remorse.

If any of you have any input (without going off the res too badly). TIA.

[HummerMann]

Orange Crush did the Duramax upgrade a few years ago and it took a few months to complete. I remember his saying the electrical hookups and wiring were the hardest part.
I recently got a quote on putting a Chevrolet Ramjet 502 (502 hp and 565 ft lbs) in my 220,000 mile Hummer for $16990 and they said they could do it in two weeks and it was pretty much a lift out and bolt in operation. The biggest installation cost would be fabricating a plate to adapt the engine to the transmission which I had rebuilt 20,000 miles ago.