This is the wet end portion of a 3 HP Executive 2-1/2" suction, 56Y frame spa pump. This is basically a pump without a motor.
This wet end is used with a 3 HP, 56Y frame, thru-bolt style motor. The motor used may be either a single speed or a two speed. The wet end may be rotated 90 degrees to change the discharge position.
The inlet is standard 2-1/2" buttress and outlet is standard 2" buttress threads. See below for exact dimensions. This has a center inlet and side discharge.