I have a 89 Iroc-z with a standard rear end and drum brakes. I have access to a posi. rear end with disk brakes (same year) What all brakes wise do I have to change. I have the complete donor car.

 

First off you have a 10-bolt 2:73 rear with drum brakes which was stock on Auto 305. Now if its a 89 with discs (11.655 rotors & alum calipers) and the ratio (2:77) in all likelyhood its a BW 9-Bolt. I made this swap myself and if you have everything complete on the rear, you will just need the Proportioning valve and Parking brake cables. Those are the major items besides the brakelines being different. Its a strong rear with the best brakes even if it is a 2:77 ratio. Good luck.