I have an 03 chevy EC with a 5.3 that I am modding out but it is a peg leg

I need to install a posi unit so I can do some serious asphalt burning

I have looked on the moser and eaton websites and I cannot make heads or tails of it

So you smart rear-end guys out there could help me out by letting me know what I need to buy. some places tell me that all I need is a diff, but others say I need a diff, gears, bolts, all sorts of things I know nothing about. HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

THANKS YOU GUYS