What size tap is the blue winged drain plug on the bottom front of the fuel module?

​​​​​​​Thank you....

one is, you better be exact for drilling a hole in the module getting dead on for the water cavity. The blue drain plug size is .500 - 13

one is, you better be exact drilling a hole in the module getting dead on for the water cavity. The blue drain plug size is .500 - 13

Thank you. When I found out yesterday that it was half 13, I tried deleting the post but couldn't. I wasn't drilling into the module. I was just chasing the threads. Thank you for your help