The reason for the different P/n and motors and transmissions is, EACH slide rack has different parameters. The torque rating and RPM of the CORRECT slide/trans is important for the operation of the slide rack system. I have never swapped another motor/trans in place of the correct one. I HAVE replaced Incorrect Powergear motor/trans because another service center tried to adapt and the motor/trans was not strong enough for the application. If you can get your money back and spend 1/2 price, it would not hurt to try the cheaper motor. Doug