We forwarded your e-mail to the Senior Manufacturing Engineer for Super II pumps and he is surprised that you have two impellers with different threads.
The factory Engineer asked that you send back two or three samples of these impellers for evaluation here at the factory. We are not sure how many you have but please send at least one if that is all you have.
Also, have you tried installing another impeller to see if the threading is also different? Please advise.
Feel free to contact us if you have any questions, comments or concerns. We await your reply in order to proceed.