I have my last two, new-in-box wheel cylinders for sale. These are vintage Wagner units, quality made in the U.S.A. from some years back. This complete set fits 1962-1966 Buick, all big series cars, including Riviera. I have one right front and one right rear available as a set. If you have any doubt about fitment for your Buick, just PM me and I'll check my old Wagner catalog.
These are genuine made in U.S.A. units. Most all brand name wheel cylinders available today are sourced in China or Mexico, and made from recycled iron that can be quite porous.
The price for this set of two new-in-box wheel cylinders is $45, plus shipping. Thanks for looking. John