2007*2008 and newer gmt900 3/4 & 1 ton trucks had 6L80e's or higher (my truck's RPO tag says 6L95e)
They had classics and nnbs in 2007. Mine is the first year for the 6 speed. Also it feels so much faster than my turd 5.3 truck. The 6l80 in the first years apparently had issues. Mine does some odd upshift down shift stuff 2-3. It’s like it has to think for a second if it wants to upshift or stay in second when I let off.