reply to preston
I second the question from robbin whether you are sure that it is the motor and not just the capacitor. While fan motors can and do go bad, it is much more common for the run capacitor to go bad.
If it is indeed your fan motor that needs to be replaced, you posted many but not all of the required specifications. Ideally you can locate the A.O.Smith model/part number. Otherwise you will also need to know the details for the motor shaft (diameter, length), rotation, speed(s), motor size and mount (frame number) to find the correct replacement.
Edit: I bought an A.O.Smith fan motor online and for the smaller motors like yours the price is in the $80 to $160 range. Expect to pay around twice that much at a HVAC repair service. The run capacitor is in the $5 to $10 range and unless it is still new should probably be replaced as well.
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