6L80 Transmission
 

I'm thinking about a new to me truck, and am looking at options. Well, more trying to figure out the details. I'll be looking for a 2008-newer black Sierra quad cab, 5.3L Z-71. I'm having trouble finding out what options the truck would need in order to have the 6L80 transmission in it. A buddy of mine has 2008 Sierra extended cab and it has the 4-speed. I've had my '01 since new and have always wished it had at least a 5 speed in it.

Also, what rear gearing was offered with the 6L80?