I am trying to find the rubber seals that clip on the body at the back of the quarter window on a 1970 Cutlass Supreme. The closest I have found are the SFT 5023 that are used on Buick and Chevrolets. Does anyone know if these work on my Cutlass or where to get the correct part? If there is a better place for this question feel free to move this post.

 

Google is your friend.
Where did you get that number Summit?

With Oldsmobile you need to go to specific suppliers for the right parts.
Otherwise you will be guaranteed to receive chinas best will-fits-all dumpster fodder.

Steel Rubber https://www.steelerubber.com AND its made in the USA. Read their home page.
Fusick, but they are likely made by Steel and twice the cost.Or maybe chineasium?
https://www.fusickautomotiveproducts...p?number=CK70A

 

The shape of the rear quarter is different for each division's cars and Chevy/Pontiac parts will not fit Olds.

 

The window sweeps at the bottom of the window?
Do you have the B85 chrome trim on the top of the door/quarter? I think most or all Supremes came with that trim. The trim is unique and requires a different sweep and is very hard to find. Restoration Specialities - https://www.restorationspecialties.com/ - has the right variants. e.g.
https://www.restorationspecialties.c...t_p_37421.html
"special moulding" is the B85 chrome trim. Their catalog used to be more descriptive but they removed the Cat Whiskers section it seems.