2.5NA temp sender thread size? (PRC3541)

[samc88]

As above, does anybody know the thread size for this sender?
http://www.paddockspares.com/prc3541-temperature-sensor-red.html
I have the earlier smaller sender and a plug in place of this larger one, I want to fit another temp sender to go to my gauge so want to get a reducer that fits (failing that I'll just drill and tap the plug thats in the head)

 

[samc88]

Found it! Apparantly it gets used on other things.

Anyway its M22 x 1.5 if anyone else needs it

and luckily they do make an M22 x 1.5 to 1/8NPT reducer