need info on tranny drain bolt

[IHateHacks]

I hate to hijack this post but, the same exact thing happened to me. Must have been the hack that last put his worthless mitts on it because it was sure as hell on there pretty fuckin tight. Must have used an impact gun to tighten it. People that use impact tools on aluminum threads should find another job, for real. You know they make torque specs for a reason....

Changed the fluid 3 months ago, noted that the plug didnt hold the specified torque of 30 ft/lbs, but said whatever. Noticed it leaking today.

I used a 15/16" wrench to take it off and put it on but Im sure thats not the right size and seeing how my mm set stops at 22mm I have no way of knowing if it is in fact mm.

Last time I checked, they dont even make helicoils that big, biggest ive ever seen was M10 and this trans drain plug is at least M20, probably bigger.

So does anyone know how to solve this?

Edit: Ok found these sizes

M20 x 1.5, M20 x 2.5, M22 x 1.5, M22 x 2.0, M22 x 2.5


So the million dollar question now is, what size are the drain plugs threads?