Im wondering where the scene that has Zack and Cloud on a truck and Zack is telling Cloud about his life comes from because I just watched Crisis Core and its not in there any ideas

It is in the secret cutscene in the original Final Fantasy. It is also in the ova Before Crisis(?). In Crisis Core it is towards the end, and is quite amazing. It is right before the scene where Zack fights the tanks and soldiers and helicopters all by himself.