[crashz]

My 2012 is peppy with or without a load in the back. Hook a trailer to it, and it has me wanting a little more grunt. I typically tow 6000-7000 lbs a few times per year, for a few hundred miles at a time. Total combined weight about 15K. Kind of wish I got the Duramax. but I don't tow that often, and it is perfectly adequate when I do.

This is assuming the 6.0 and the 6.2L engines perform similarly.

If I were building a truck to tow, I'd go 8.1L or Cummins. I'd want the Allison to go with it though. The 4L80E didn't come with the 8.1, unless it was in the van I think.

One word of warning, and this is second hand info at best; but the 8.1L motors seemed to have some oil burning issues. Seems like some guys on other message boards had to rebuild their engines because of excessive oil consumption and piston slap/scuffing. I have not hand any first hand experience with these motors so that could just be rumor or bashing.

What about rebuilding the 454 and adding aftermarket (like Holley) FI? Not really original, but it will give you a strong truck with dependable power for a reasonable-ish price.