Anybody know if a posi rear end with 3.23 gears out of an 88 IROC will swap right into an 83 Z28???

 

9 bolt to 10 bolt, no. 9 bolt to 9 bolt yes, 10 bolt to 10 bolt yes. make sure the carrier series is the same.

 

i dont think the old one is a 9 bolt, but if it is, can anything be done to convert to 10 bolt? also its a rear drum to disc conversion with all the hardware on the rear end. Do I need new proportioning valves/master cylinder, brake lines?

 

If you are talking about swapping the entire rear end it will bolt right in, However you will need the proportioning valve also from the disc donor car.