I have a 1946 big bolt. I replaced all the wheel cylinders and brake linning. I checked for a new master cylinder and realized for under fifteen dollars a I was able to rebuild the oringal one under the floor board. I can send some one through the windshied with the rebuilt master cylinder. I always believed that if its not broke don't fix it. Try and rebuild the one you have first and try it. Oh by the way, I was able to get the rebuild kit at the local Car Quest supply parts store.