1991 Other Nissan Models truck problems

I have a 1991 Nissan pickup truck, I was driving and the engine over heated stopped to check it fluid was low added antifreeze to radiator and over flow tank. Tried to drive again and overheated right away. Check engine again and noticed antifreeze in the air filter. Thought it was a cracked head gasket but not sure. what can I do to solve this do i need a new engine or not. I saw a prduct call like steel seal wondering if that works or not. Thanks