[minytrker]

I hope you know more about cummins than 5.3's LOL. It depends what the 5.3 was in. A 99-2006 silverado 1500 had the old iron block normal 5.3. In 2007 they started putting aluminum 5.3's with active fuel management in trucks. In 2005 envoy's and impala's got aluminum 5.3's with active fuel management going off the top of my head. My 2006 1500 has regular old iron 5.3. I dont think variable cam phasing came out until 2007, but Active Fuel Management came out in 2005. Some motors have both, but only the aluminum one have it I think.