Working on the /6 conversion last night and just happen to look at top of the transmission and see this little plug sitting there next to a similar size hole. My first reaction was one of "WTF is this?" My second was, "How long has that that little plug been there and how have I not lost it?"

Anybody have a clue what this is and how it popped out? I could stick it back in but it'll probably just pop out again. Probably better to tap and plug it.

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Breather port?

No, that's on the other end of the transmission.

This little plug and hole is on the top of the intermediate plate.

???

Clean it and the hole up and maybe it will be more clear.

Ok, now cleaned up and a few more views. The "plug" isn't a tight fit in the hole but definitely looks like it came from there.

The hole appears to be counterbored like a plug was supposed to go in there. Maybe there's supposed to be a pin or spring in that bore?

Here's a few more shots. One backed up so you can see where it is on the case.

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Looks like PO mistake to me.

VEDDY EEENTERESTING TOM!

Does that intermediate plate look like aluminum? Or Magnesium...

My first thought was that it was drilled for trans cooling/recirculating/spraying of oil, but that seems like an unusual place, unless it hits directly over the input shaft bearing.

Looks like a cross drill hole for something internal, factory probably plugged it. Pretty common on castings of all sorts, like the oil galley plugs.

Looks like a mistake Never seen one of those.

Maybe it's just trying to make a statement?

That's where the little people leave their home on the way to tend their rust farms.

Magnesium, but I know where you were going with that.

There is/was a aftermarket intermediate plate.

Probably a mistake that he plugged and the internal pressure was enough to pop that plug.
JB Weld

Rich

Yea, it is interesting because the hole is neat and clean, not like someone drilled it (at least not half assed) and there's a step to it. A PO drill job would have gone right through without stopping, I would think.

I was able to get enough purchase with a 6mm tap to thread the hole. I'll use a threaded plug with loctite to seal it up.

I also checked the main breather and it was clear.