What bolt is this?

[Disturbance]

The big one in the middle, this is on the passenger side transmission it's leaking gear fluid, is this the drain bolt? And what size is it?

 

[campos_racing]

You might want to check this thread.

http://www.columbusdsm.com/forum/showthread.php?t=16688

 

[19Eclipse90]

http://www.dsmtuners.com/forums/newbie-forum/401312-trans-fluid-capacity.html#post152569635

And I'd suggest using this since it actually lists that bolt's size -- it's the same on a 2G: http://www.dsmtuners.com/forums/articles-miscellaneous/437697-what-size-bolt-nut-stud-fastener-1g-version.html

 

[Colt4G63 also]

Yup, it's the drain, and it looks like you may be missing the crush washer.