Hey Kev, welcome back. Looks like you went into hibernation since 2019 when looking back then. Are you shopping for a replacement or finally getting to the task at hand?
The Denali will be AWD until 2009 no matter what.
In 09 the Denali offered 2WD or AWD.
The Denali is a almost a debadged Escalade and loaded.
Every Denali has the 385hp 6.2L. In 09 it went to 405hp, In 2010 they added the AFM or cylinder deactivation.
The Tahoe has the 2WD 4WD option and a one year only option in 2009 of the L9H or 6.2L.
If I had to go Tahoe or standard wheel base Denali I'd make my own 4WD Denali. I'd purchase an 09 Denali to get the L9H w/ non AFM 405 hp motor. It would be loaded in Denali trim. Change the front diff and add the selector to the dash to make it 4WD. Try to find one that has one of the premium colors as the clear coat tends to stay intact.