Superior Electric is located in Bristol, Ct. The company has been producing variable transformers (Powerstat) since 1938. Later they started with the production of synchronous and stepper motors, followed by a full range of drives and controls.
The brand name of these motors and drives is Slo-Syn
This page gives you access to my collection of historical Slo-Syn Motor datasheets.
The standard type numbers are simple:
The range of Stepper Motor sizes is 60mm, 90mm, 110mm and 170mm. For example: M061, M092, M111 and M172. The Synchrounus Motors uses a torque indicator: SS150 = 150 oz/inch, X1500 = 1500 oz/inch.