There is one plastic piece per window. As for replacement there are two options, you can buy just the plastic slider for something like $6.00 and then repeen the rivet (PITA) or you can get a complete regulator which should have the plastic already swaged on and replace the regulator (still a PITA).
Tight working quarters, and when you get the lift arm unbolted, watchalo, as the arm is spring loaded. It slams home with authority. Don't ask how I know.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.