Vortec 5.3L V8 SFI, 4-Speed Automatic with Overdrive, and 4WD. Real Winner! Why pay more for less?! This 2007 Sierra 1500 is for GMC nuts looking all around for that perfect truck. The precision-tuned Vortec 5.3L V8 SFI powerhouse delivers substantial horsepower and torque to get you where you need to go...and fast! It scored the top rating in the IIHS frontal offset test.