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I have 4 of these brand new but opened NAPA 37236 wheel cylinders. Same as Raybestos WC37236. Bought them a couple of years ago for spares, but recently found some NOS USA pieces to put on my shelf. These are the China version which is all that is available now. 7/8" bore and the ones Dr. Diff recommends when doing a front disc conversion. Replacing the original 15/16" rear cylinders with these will help prevent rear wheel lockup. They sell for 24.49 plus tax. Selling all 4 for $75. shipped in the USA in a padded USPS flat rate envelope if using friends and family.
https://www.napaonline.com/en/p/UP_37236?impressionRank=1
https://www.napaonline.com/en/p/UP_37236?impressionRank=1