This appears to be the plastic piece that is affixed to the window pane itself, not part of the balance (aka block-and-tackle)
I believe the window is Pan Am. My previous order from you - 2212075 - to fix the broken balances fit perfectly.
Here isnan additional picture with the window removed.
Hello there!
The broken part in question is called a top sash guide. The 18-042 Pan Am top sash guide pair that you mentioned looks like a dead ringer for what you're searching for. You should be good to go if the specifications align.
Let us know if you have any other questions!
I'm happy I could help. Good luck with the repair and thank you for your order! I'll be here if you need anything else.
