I Got This Code Out Of A Differential But Im Not Sure If Its Right, And I Dont Know The Gear Ratio Or If Its Posi, The Code Is
2pe C051 2 How Do I Break It Down?

PE and 2PE are 3.42 non-posi rear ends used in the later Second Gen Camaros and Firebirds. These codes were used for a number of years. Madmike has the full list if you start at his main page and check each year.

Ok So Its A Non-posi What Do I Need To Make It Gary Posi?

You would need to add a posi unit to it. New they run about $400, plus installation parts and professional labor, it could run as high as $1000. Usually it is cheaper to find a rear end that already has posi in it than to convert a non-posi rear.