5.7 vortec air conditioning

[HotWheelsBurban]

I don't know anything about whether the mounting holes are different, but electrically you shouldn't have any problem

The mounting setup is definitely different on the 800 trucks. On my dad's 06 Denali, the blower motor fits into the housing by way of threads in the housing, and the motor case has corresponding threads. It takes longer to get in position under the dashboard than it does to replace the motor. There's one screw that holds the vinyl cover over the blower motor housing and a tab that holds the other side in place. Take the cover out of the way and you have access to the motor. Unplug the wiring harness and unscrew the blower motor, then screw the new one in. Wish it was that simple on our trucks....
This and the ease of changing headlight bulbs are the only ways that GMT 800 trucks are " twice as nice " as the 400s!