Part Type: HVAC Heater Core. Aluminum Heater Core. Heater Core. 2007 GMC Sierra 1500 Classic Submodel: Crew Cab Pickup; Engine: 4.3L V6; Except RPO Code D07; w/o Rear Vents In Center Console;. 2007 GMC Sierra 1500 Classic Submodel: Crew Cab Pickup; Engine: 4.8L V8; Except RPO Code D07; w/o Rear Vents In Center Console;.