M-135/M-211 have no check valve, M-35 does, Some CCKWs use the check valve, but when the type 3 Hydrovac Fat One) is used, the check valve should be removed, as it is in the Hydrovac. There is no reason for Wagner Master Cylinders having different dimensions, but some of the Off Shore Cheapos that some places peddle could understandably vary. I will not sell off shore brake products, they have a history of flaws.
