the same one. One method is to use a Sharpie type marker and mark the belt as it sits on the CAMs. As long as the CAMs are only moved a little bit (ie., tension relieved on psgn side) the belt can be re-installed using those marks.
Have used this technique on other cars with good belts where the engine needed a water pump, tensioner, etc. Just a little bit harder on the Z engine since it's got more going on than a simpler 4 cylinder econo box engine.