My new Pentair Dynamo arrived yesterday. According to the drawing below from Pentair's website the output should be a 1.5" female NPT. There are female NPT threads on the output port but there are male threads around the outside of the port as well. There's no indication of them on the mechanical drawing. Are these mystery threads 2" male NPT?
EDIT: I've established that it's not 2 inch NPT by comparison with a known 2 inch male NPT fitting. My current thinking is that it's a thread for one of these "1/2 union" things. I don't quite know what they are though!
I was also surprised to find that the motor came with a (low-off-high) switch backplate. Like the mystery port, there was no indication of this in any of the Pentair literature I've seen. It was a pleasant surprise since I'm already wired for a plug-in pump and I was expecting to have to direct wire and do my own speed switch.