what size is the tranission drain plug?

[jrguzmanr]

So I'm here with my truck on jack strands thinking I had it all figured out and now I realize I don't have the socket to remove the tranmission drain plug? What size is it, so I can go and buy one.

edit: I took a closer look and, I'm not sure how to describe this, but where I remove the filler plug, seems to be stripped. I can't see the "star" that I was expecting. Do i need a new plug? Where can I get one?
thanks

 

[Black Dynomite]

Mine takes a 22mm socket for the drain plug. Does sound like you need a new plug, no idea where to get them sorry.