The last year for the LQ4 was 2007. And it was in a 2500hd classic. It’s a 2007 truck, but it looks just like a 2006. I will assume the 8th digit of the vin is a U.
The new style 2007 truck would have a LY6 and a 6L90E. The LY6 is a Gen IV motor.
You have a desirable motor, but the PCM cannot control a 6 speed.
https://en.m.wikipedia.org/wiki/LS_b...l-block_engine