I have been having problems with my the block heater on my 782D I got this from a Kubota dealer and they sold me the wrong thing I got a threaded insert that pounds into a freeze plug hole. It was too large for the hole so I machined it to fit. The problem is it is a 1000 watt heater and it is at the top of the engine and coolant doesn't circulate and in a while the cord gets too hot, gets soft, shorts out and blows the breaker. What I am planning on trying is at the top of the head where I have the 3/4 NPT threaded hole adapt this down to 5/8 and attach this to the output side on a 700 watt circulating tank heater the cold intake will go to the threaded hole on the drain petcock. What is the thread size of this hole? Are there metric pipe threads? I can't take this off without raising the motor so I would like to know if this will work or maybe I will re-thread it to a NPT size I can work with. The petcock is part no. 1285 554 C1