I am in the process of changing my tranny fluid. When I dropped the pan down there was a plastic plunger looking thing with an o-ring around it laying in the bottom. What is it and where does it go?

 

It is a filler pipe plug used from the factory. They just knock it in when they install the trans. Don't worry about it.
Alan

 

Okay, Thanks!!

 

OMG! Thats the Dis-Come-Bob-Ulator Higa-Majig that plugs into the Pisshotty Valve! By removing it your transmission will now evaporate!

I wish I had a picture of everyones face each time they see this plug and not know what its for!