Size of Automatic Transmission Fluid Drain Plug

Does anyone know what size and type of thread the drain bolt is?

I've googled that crap out of it and can't seem to find it anywhere!

I'm looking at the possibility of installing a temp sender into the drain bolt instead of tapping into the cooling line.

I really don't want to remove it, just to measure it and see what thread it is

 

The drain plug is 14mm I believe. The drain and the transmission oil level check I'm pretty sure are the same size. With the engine running and transmission warm, you should be able to remove the transmission oil level check plug without loosing much fluid (it's actually part of the fluid level check procedure). But that way you could remove the plug, have a look, then put it back and decide if you want to use the drain plug for your little project.