Hey Mac55,
Just keep in mind, the one piston wont budge cause it might be a left hand threaded piston. i learnt the hard way on my car. The right rear pushed in no problems, i then moved to the opposite side and battled my @rse off. Eventually popped the piston out and found out it had an opposite hand thread...Dont fiddle too much, try figure out first, you can turn the piston back with a decent pliers or by hand.
Hope it helps.