I could use some advice on whether I should replace all four wheel cylinders or just the cylinder that is leaking? Full disclosure this is for my ‘64 Imperial Crown Coupe, not a letter car, but figured the advice would also be beneficial to letter car owners as well.I discovered the driver side rear is leaking and set out to replace ALL the wheel cylinders as a “preventive measure.” When I checked the condition of the other three cylinders, they all appear fine but I suspect they’re old - “Wagner Lockheed - Made in USA” is stamped on the housing and we all know how few automotive parts are made domestically these days.Question: should I “leave well enough alone” or is there some benefit to replacing all four at once besides knowing they’re new?I suspect hygroscopic DOT 3 brake fluid was previously used and the car sat for the better part of 20 years…some clumpy viscous residue in the bottom of the master cylinder. I was thinking replacing all four wheel cylinders would aid in a brake fresh and upgrade to DOT 5.I appreciate the feedback and help.Kurt