Auto transmission plug gasket

[MarkM04]

I've bgeen draining/fill my transmisison fluid a few times now, just re using the original plug gasket. Well, I just did it again, let it sit over night, and it's leaking.A year or two ago when I bought the fluid at the Toyota dealership, they couldn't find the gasket in their system. Anyone know what size it is? I guess I could just take it to the parts store, and see if I can match it up with something.

[MarkM04]

I tightened it up a little more, and it stoped leaking.I'll find out the size next time I do a drain, and post back.