Enjoy! Here's a copy of the 2007-2009 GM/GMC factory service manual for trucks. It covers trouble shooting and advice on what and how to repair/rebuild everything with torque specs.
4.3L engine to 6.6L trucks with everything form bumper to bumper...
https://www.dropbox.com/s/rflvemxjpqfc4h4/Gmc_Sierra_Service_Manual_Repair_Manual_Fsm_2007-2009_Download.zip?dl=0