This article explains how to connect the vacuum source from the engine to the wiper motor. All 1955/56/57 models are the same except for initial vacuum connection to the engine.

The 1955 model (shown) receives vacuum from a brass fitting in the manifold forward of the carburetor. The 1956 model receives vacuum from a dual brass port fitting at the rear base of the carburetor, the 1957 model receives vacuum from a brass fitting in the intake manifold behind the carburetor. If the car is equipped with power brakes an additional port is supplied at the same fitting. A non power brake car is shown.
A metal vacuum line from the engine is routed down to the fuel pump and connect to the top of the fuel pump outboard port with a short rubber hose. The upper portion of the fuel pump is designed to boost the vacuum to the wiper motor.
A metal line connects to the inboard port of the fuel pump with another short rubber hose. This metal lines is routed up and half way past the driver's side of the intake manifold. A rubber hose is then connected and routed through the firewall.
After the rubber hose passes through the firewall under the dash it is connected to the top of the wiper motor port that points to the passenger side. The bottom port on the motor is an open vent and not a connection. A "T" fitting is installed in the hose which supplies vacuum to the heater vacuum control valve inside the metal heater chamber.
The curved wiper arm connects to the bottom stud of the motor arm and then the driver's side wiper pivot. The straighter arm connects to the upper stud of the motor arm then the passenger side wiper pivot.

Gil Baumgartner