I am changing the rear brakes on 97 monte, left side went great but the on the other side the piston will not push back in. Any ideas?

Are you using the caliper piston retracting tool? Inward pressure is required to retract the pistons, watch your direction of rotation.

I am changing the rear brakes on 97 monte, left side went great but the on the other side the piston will not push back in. Any ideas?

With these calipers, you are supposed to turn the piston as you push it inward. Clockwise to retract the piston. If it doesn't move freely, it could be the piston is froze and you either need to rebuild the caliper or replace it.

thanks for the help, worked great. By the way, is there a special tool for this, if so how much, I used a needle nose pliers, slow but it worked.