>From the WPC News> Kelsey Hayes (Master cylinder with power brake booster) rebuild kits. Fits only 1955. Includes large diaphragm. Impossible to find until now. Newly manufactured rubber parts. Jim Fredrick, 918 W Co. Rd. Roseville, Minn. 55113. (612)484-1184. The last time I purchased the kit, it sold for $125.00. I have found, the primary problem to be a ruptured large diaphragm. How ever it is not available to be purchased separately. I have a complete "Core" unit if any one is interested in a spare needing rebuilding. That's All Folks Jim ... 1939 C24 Limousine