Originally posted by compaddict
Does anyone happen to known what it is?
No, but I'll wager it's metric! Since metric threads are all measured by the outside diameter of the thread, a set of vernier calipers will give you the diameter, and a metric ruler will tell you the thread pitch which will be a multiple of 0.25mm. Purely from memory, I'd guess it's probably M12x1.75 or M14x2.0; maybe even M16x2.0.