So I changed my 97 ford explorer's transmission fluid today. While doing so I found a strange little plug like part in the bottom of the pan. Its in the shape of a mushroom, and it is yellow. It is about 2 inches long, and the "cap" is about about 3/4 Inch diameter. Towards the bottom of the "mushroom cap" theres a black o-ring. the top of the cap looks to be drilled out...It reminds me of a plug, but I can't figure out where it came from. Has anyone seen this or does anyone know what it could be? I put the new trans. filter and the pan back on, filled her with fluid and it runs and shifts fine. I'm kind of wondering if the previous owner may have dropped it in there on accident or what.. (is there a way to post pics?)

 

That's the tranny fill plug installed when the tranny is going thru the assembly line. It gets popped into the tranny when filled at the factory. It doesn't hurt anything. What it does do is tell you that the tranny pan has never been removed before for filter change or anything else inside.