What model transmission do I have?

Excuse me for maybe being naive, but how can I tell what automatic transmission I have. I figure it's either a 4l60 or 4l80, but don't really know for sure. I sure wish I knew how to tell.

The truck is a 2007 Avalanche Z71, 4x4, 5.3, DoD, E85.

Thanks!

 

i may be mistaken but i think the 07s come with the 4L70e.

its not an 80e for sure, either a 60e, 65e, or 70e