1972 polara, Looking for how to remove window roller hardware or where to buy

[72polarbear]

I have a 1972 polara with the passenger side missing one of the rollers which leaves to swing side to side. I have a 4 door parts car that I want to take the roller from but after getting the front disc to turn it doesn’t feel like it’s getting loose. Is there a specific way to remove them or should I just buy new ones and if so, where?

 

[72polarbear]

Update: got the hardware and installed it by getting a little creative with a grinder. The door was all opened up and cut as the sheet metal was used to fix up the previous owners bondo work. As for installation I really didn’t want to take apart the doors and drop the windows so I slid the screw and the plastic retainer through the rail, cut a slit into the spacer just big enough that it would have to flex slightly to get onto the screw then screw on the top disc by wedging a flathead through the Chanel and against the retainer and tightening the top disc to the window, for that I used the tool that comes with angle grinders and put a prong into one of the holes and the other against the edge of the disc and tightening it. At the end the window sits perfect, I will update if any problems arise.