Flash Backs

As evreyone knows Zack is seen in a truck with cloud and running in a sandy area well i think i know were that is ill post the whole thing from the original story

Cloud is assigned to guard Sephiroth on a journey back to Nibelheim to investigate the Nibel Mako Reactor upon hearing of monster attacks. Sephiroth is accompanied by Zack, a member of SOLDIER, 1st class. Zack apparently has gone out with Aeris some time in the past.
Sephiroth and Cloud take Tifa as a guide to the reactor (Cloud not revealing his true identity). Sephiroth discovers the monsters in the reactor and begins to doubt his origins. He discovers a secret library in Nibelheim where he finds out the truth about himself. Overwhelmed by the new information, he goes on a rampage and burns Nibelheim to the ground. Zack and Cloud follow him to the Nibel Reactor to find that he intends on joining his mother, Jenova, in a quest to take over the world.
Tifa takes Sephiroth's Masamune sword (which he has carelessly left) and attempts to stab him for the death of her father. Sephiroth gets the better of her and slashes her, leaving her on the ground. He enters the inner chamber and takes Jenova's head from its stasis container. Zack arrives to attack Sephiroth and is also stabbed and lies wounded. Cloud, overcome by emotion, puts Tifa to one side, takes Zack's sword, and attacks Sephiroth. Cloud is deeply injured by Sephiroth's sword, but in a haze of emotion, somehow manages to grasp the sword by the blade and throw Sephiroth into the Lifestream beneath him.
Sephiroth drifts through the Lifestream and ends up in the Northern Crater, frozen.
Tifa is rescued by her martial arts instructor, Zangan. She makes her way to Midgar, where she opens a bar in Sector 7 called Seventh Heaven.
Zack and Cloud, both barely alive (though Zack, having a stronger constitution, is healthier) are captured by Hojo of Shinra, taken to the basement of the Shinra Mansion, and used as part of his new experiment, to attempt to create Sephiroth clones (most of the victims are from the ruins of Nibelheim). All previous clones are failures, resulting in a vegetable-like state. Cloud does not take to the treatment, lacking the willpower. Hojo labels him a failure, but keeps him around.
When a guard comes to give Zack his food, he knocks out the guard, rescues Cloud (who can barely move) and hitches a truck to Midgar. After debating with himself, he decides that he and Cloud will become mercenaries (the words echo in Cloud's head). However, before they can reach Midgar, they are chased down by Shinra soldiers. Zack is shot dead, but they leave Cloud, the failure. Cloud manages to crawl to Zack's body and take his sword.
Sephiroth finds that he can control his attempted "clones" with his mind, although he cannot make them do anything of any value due to their state. However, he finds that he can control Cloud more subtly but more effectively due to his "failure" status.
Cloud's mind, awash in pain and fear, constructs its own version of the facts, in which Cloud takes Zack's position in the occurrences, and becomes a member of SOLDIER, 1st class. He also glosses over his friendship with Tifa as if they were best friends. He somehow manages to make his way to the Midgar train station. Tifa finds him there, and decides to watch over him for a while.
Shinra orders Nibelheim to be rebuilt and populated with Shinra staff, there to oversee the actions of the Sephiroth clones from Nibelheim. They are ordered to pretend no catastrophe has ever happened there. Hojo takes Jenova from Nibelheim and ships it to Shinra HQ in Midgar, minus the head that Sephiroth took with him.