Product review (4 stars): UPPER vs LOWER fan selection...
I did not purchase this item from Amazon, but I learned some things by ordering the WRONG part from another retailer, due to a confusing (and possibly incorrect parts diagram) for a Samsung NE58F9500SS/AA slide in oven.

This fan motor (part number: DG31-00005A) is the correct  motor for the LOWER convection fan.  It should have reverse threads on the shaft, since the fan blades turn clockwise. ( I cannot verify that this particular item has this feature however).  The sticker on the motor body in the photo (SMC-U386A) is correct for the LOWER motor that came out of my stove.

The fan motor for the UPPER convection fan should be part number DG31-00007C.  It should have standard threads on the shaft, since the fan blades turn counter clockwise. The sticker on the motor body should be SMC-U386C.

the two motors are very similar, but NOT interchangeable.  They CAN be disassembled, and the rotor/shaft direction switched to make them work if you screwed up and bought the wrong one like I did, but the original cap nuts won't fit since the threads will be backwards .....

switching them out is EASY if you have the right parts.  Hope that helps someone!!