Welcome back, you can tell from casting numbers on the back of the block, right above the bell housing then decifer them at mortec.com or moretech.com. Edit your hot rod in your profile to 1979 Camero cause that Firebird's long been gone. Take a pic of the engine and the car to show us what u got. It's probably a 350. To get the numbers without removing the engine, you may be able to get some clay and push it onto the casting numbers, then hold it to a mirror and right them down.