O-ring size?

[jdavis2]

Any one know the correct o-ring size for the dip stick tube on an A904? Mine was leaking so I pulled the tube and found the o-ring that was on it to be damaged. I've got one from work that looks like it ought to work but after pulling this one and draining a quart of tranny fluid all over the garage floor I'd kinda like to only have to do it once.:|

 

[Guitar Jones]

It's a standard size o ring. The dealers should stock them but I don't know what size it is.