i have a 92 trans am that has drum brakes in the back and would like to go with a disc rear and posi. i found one at the junkyard that looks pretty good with disc and everything off of an 89 trans am would this work with no problem also with i have to change anything else to hook up the rear disc ?
or would it bolt up connect the brake likes and vamonos?
here is a pix of the rear end i found

 

Basically, a direct bolt-up; no modifications required that I'm aware of.

Even the prop valve is the same, in your year, for both drum and disc; because the bydraulic requirements of the PBR calipers are about the same as drums.

Make sure they don't cut the parking brake cables; have them disconnect them from the "equalizer" thing in the tunnel, UNDAMAGED.