Generic Replacement, No Flange 1959-1996
Pella Original, No Flange 1959-1996
Pella New Style, With Flange 1991-Present
You should be able to feel around under the door to see if the flange is there. I have used the generic and found it to be good quality and fits just like the original. But if having original parts is worth it to you, look at
81-098 without flanges, or
81-244 for the one with flanges. I have only seen these 2 types of rollers referenced to Pella. If you know of others, I'm curious.