Did a 41 Ford big truck recently and had to rebuild the existing wheel cylinders. Found the rubber cups at American Power Brake in Dallas, Texas and dust seals off of a later model Dodge. Bored and sleeved the cylinders and made the aluminum pistons. Check Hemmings for "Services Offered" as there are ones that rebuild cylinders---Apple Hydraulics for one and, they may stock parts for old cylinders and most likely stock parts by size rather than brand. Sounds like a fun old truck; good luck.
