Gould 1 HP K56I Frame Electric Motor, 60Hz, 115 V, 1 ph , 3450 RPM. As indicated by the K56 frame designation, it has a 5/8" diameter shaft. The shaft has a key slot. The motor is quite clean, and in great operating condition; it starts and runs very smoothly with no vibration.
A bottom mounting bracket is welded to the casing, with four elongated bolt holes, spaced about 3" center-to-center.
Update: I've added a picture of the wiring diagram (last listing photo), as it appears under this motor's wiring box cover. It shows that this is a dual voltage (115V/230V) motor, with illustration of the wiring connection for each choice. It also indicates that this motor is not reversible.