ok this is the problem. I'm going to change from a 2:73 gear to a 3:73 gear. this kid at a local atuo shop told me in order to do that i would have to replace the stock carrier which I wanted to use for a 3 series carrier?

Is the carrier in a z28 with 2:73 gears a series 2 and do i have to buy a new series 3 carrier or can I use a spacer on the the stock on?

 

Correct, you have a 2 series. You can buy 3.73's for a 2 series carrier. Look in Jegs or Summit. They have a thicker ring gear so a spacer is not required.