Part was an early take off part from an old salvage yard that I bought Tons (Literally) of old parts many years ago and have packed away in my buildings.  Part is in good used condition. I have only crudely tested it in feeling the condition of the rubber bellows and depressing the brake pedal and putting my thrum on the vacuum inlet.  It appears to hold vacuum until you release your thumb.  Assembly may have to be restored to be excellent,