Weeping gearbox

[Fin]

I have a weep from the top cap on my gearbox.
I was in MrT's yesterday, picking up filters and oil, but he couldn't find a listing for the O ring.
Would anyone happen to know a part number, or where I can get a suitable replacement?

[Joesson]

Not helpful for your part search but for your info.
The " Top Cap" on your gear box is a redundant opening on the MR2 arrangement.
I understand it is to take a speedo drive on other vehicles that use the same engine.
It may look like a gear oil filler orifice but I am very certain that is not what it was designed for.