temp gauge sender

20211020_140419.jpg Hellooooo FABO!

I have my temp gauge sender here on the water pump housing. I am having trouble figuring out how the wire attaches. I crimped an end on the wire, but not sure what thread that is. I tried #10-24 and 10-32 with not luck. No damaged threads. Is this one of those slide on connections? the little rubber/plastic piece at the base of the threads leads me that it might be. If a nut came with the sender, I lost it long ago. Small little stupid thing.:BangHead:

Thanks Ladies and Germs....