** Please Note **
Replacement motors may or may not come with the shaft internally threaded as the original OEM motor. It is not a requirement for replacement motors. Replacement motors are copies of OEM designs and the tapped hole exists only because OEM customer requested it. Since certain replacement motors have been released having this feature, some customers have come to expect it assuming that the threads are necessary or there will be a problem with the impeller coming off. This is not a correct assumption. AO Smith has built replacement motors without the threaded holes for over thirty years and is not aware of any case where the impeller has spun off. If the lack of a threaded hole remains a concern, they suggest using Loc-tite or a similar product to alleviate the concern.