Can you post a picture?

Is it like this one?

https://www.gmforum.com/buick-172/he...ration-306842/

I think I know the ones you mean. I've only ever seen a few of them. I wonder if the seals are the same as on the non-ABS version.

Where did you find the replacements?

I remember seeing a few of these . . . and wondering what GM was smoking during the design phase. I wonder if they use the same seals.

Yes it is the one in the picture. I found an exploded view of it with the part numbers on Nemigaparts.com website. You have to type in C Brake Master Cylinder-Antilock (Teves)(JM4) in the search box. I was able to find the seals on gm parts giant website part number 25528394. You have to know the part number is order to find them. The seals are not the same as the non-abs. I wonder what a lot of these cars designers are smoking. A lot of these newer model cars have more problems because of design than older model cars do.

Cool, thanks for the information!

I'll keep them in mind for future hard-to-find parts requests that come across here.