* 4.3L Vortec 4300 V6: This was the base engine.
* 4.8L Vortec 4800 V8: A popular choice.
* 5.3L Vortec 5300 V8: Another common and slightly more powerful V8.
* 6.0L Vortec 6000 V8: A larger displacement V8, often found in higher trim levels or those with towing packages.
So there's no single answer; the engine size depends on the specific trim level and options of the truck.