need help with removing ignition lock unit!!!!

[tranz am]

OK Im really irritated about this. I have to replace the ignition lock cylinder in my 69 gmc and I cant freakin remove it!!!! I figured that all I had to do was turn the chrome ring on the front of it. Made perfect since to me so I twisted it to loosen it. It was fairly tight and I had to use a screwdriver and a small hammer at first. after I loosened it I could turn it freely with my hand. I kept unscrewing it until it started to become harder to twist. I kept on twisting it and ended up having to use a pair of vise grips on the ring. now it spins freely but It wont come apart!!!
Its like I striped it out or something. Can some one please help me out here Im about to use a dead blow on this thing!!!!!!