Changing rear brakes on 95 v6 problem

[Red_94Formula]

Im working on my friends 95 Mustang v6. The fool let the rear pads wear down so much they were grinding on the insides of each. It was so bad on the passengers side that there was no pad and he was grinding the caliper piston into the rotor. Anyways he needs one new caliper there. But my problem is with the caliper brackets on both sides. The lower guide pin is seized in place on both of them. The upper ones move back and forth smoothly but the lowers will not budge even with a sludge hammer. Am i right in beliving the lowers are susposed to move in and out or should they be locked in place? With the new rotors and pads on there, there is no way for me to fit the caliper on there since the lower pin on each side have siezed in the out most position.

Thanks
Derek