Just to clear up some info on Neu motors.
The older style motors had a one piece front endbell/can with a pressed in rear plate. About 1-1.5yrs ago they started using small screws to retain the rear endbell.
The newest batch of Neu motors appear to have a threaded on front endbell with small set screws capturing it, and a threaded or pressed in rear endbell with small set screws capturing that also. I have seen this in both finned and smooth motors. I can post a pic of a pair of 1521 1y finned motors that are both styles if desired.
I personally feel that the one piece can/bell motor will be superior, but what do I know...
Plan to run one of the 1521 motors in my lst and the other in the muggy. Both 6s with MMMs and geared similar. We will see which motor fails first!