[vinniemarotta]

Is therr a difference between a 48y and 48yz frame motor?

[talaniman]

This may help and explain it.

motorsanddrives.com - Mystery of Motor Frame Size

Y

When a “Y” appears as a part of the frame size it means that the motor has a special mounting configuration. It is impossible to tell exactly what the special configuration is but it does denote that there is a special non-standard mounting.

Z

Indicates the existence of a special shaft which could be longer, larger, or have special features such as threads, holes, etc. “Z” indicates only that the shaft is special in some undefined way.

YZ seems a combination of a special shaft, and mounting configuration.