* 4.3L V6: This engine used regular unleaded gasoline (87 octane).
* 4.8L V8: This engine used regular unleaded gasoline (87 octane).
* 5.3L V8: This engine used regular unleaded gasoline (87 octane).
* 6.2L V8: This engine used regular unleaded gasoline (87 octane).
Note: While these engines can operate on regular unleaded gasoline, it's recommended to use a higher octane fuel (89 or 91) for optimal performance and engine longevity.