The 2500 Avalanche with the 8.1L was available as late as the 2006 MY. Since they went to the new body, they
did briefly offer a 2500 version with a
6.0L, for 2007, but it was not as much of a brute as the original 2500 like I had (2002 model year). I would not be surprised if they discontinued the 2500 Avalanche all together. It was not a popular seller, and the newer iteration was pointless. I NEVER saw one on the road. I don't see it on the Chevrolet website, either.
Check out
www.gmbuypower.com to see if you can find one out there somewhere as a leftover if you have to have the 2007 6.0L 2500. If you are towing more than 8000 lbs. total, just step up to the Diesel 2500HD.
www.chevyavalanchefanclub.com is the OSO of the Avalanche. They will have ALL of the answers.
You can pick up a used 2500 Avalanche with the 8.1L for in the teens. They were rated for 12K lbs. towing if set up right, and that 496 BBC is a beast in a relatively small truck.