aluminum window glide replacements

The house was built in 1973 and has aluminum framed windows. I hope you can see in the photos that I need the roller that fits ( screws in) at the end of the bottom of the frame so the window will slide open smoothly without being metal on metal like it is now. I need 14 pieces ( 7 windows) to make the repairs as all of them are metal to metal now. I looked at your inventory and comments. I think 87-020 is the right part or 87-196 ( metal).

I'd like your advice before placing the oder. Also, wouldn't it be better to replace the pieces with metal ? It seems like that would hold up better and last longer ... right?

How long does it take to get the shipment ( souther California) and what is your return policy? (in case the part doesn't work / fit?)
Thank you for your assistance. Trudy