Be very careful to check the repro valve if you get one as some have a incorrect top piston that will lock your brakes and not release them. There is only one MFG of the valves but they are sold by everyone. You can check a repro by trying to blow air through the top with the top fitting tight. If it does not pass air it is a no go. I got one of the first runs so it may be corrected by now but check it to be sure. The fix ? You can use the original top piston in the reproduction valve and it will function properly. If you get a new one get it from Fine Lines. They have done further refining on this part to make it look more original and function correctly. I talked to the owner of Fine Lines at Carlisle about the defective valves ....he said that they would work with the Mfg to fix the problem.