Tundra tranmission fill plug sheared off - replacement bolt available?

2015 4x4....Was thinking about doing a drain and fill of the ATF fluid and crawled under to take a look at things...discovered that the fill plug head is completely gone. Thanks to the PO for that one.

Its a truly awful place to even attempt to try to extract the bolt, and there is no way im drilling it out into the transmission. But the first problem I have is that it doesn't seem Toyota sells this bolt and gasket as a replacement part. I don't want to try anything until I have another bolt to put in there.

I believe its the 24mm head 'WS' bolt. Does anyone know the actual thread size and depth of this bolt, or any toyota parts that are known to fit in its place? Im not looking forward to dealing with this at all