You can find information on your existing motor label that will help you in selecting the correct  replacement.  Some important information to look for is the frame, RPM, amperage, horse power, shaft (threaded or keyed), the phase, and if your motor is a square flange or a C faced motor. 

To determine if you have a Full Rate or an Up Rate motor, here's what you need to do:

1. Find the motor's service factor (S.F). The service factor number and horsepower of the motor, can be found on the label that's on the motor.
2. Use the information found in step one to use on the chart below to identify the rate of your motor.