Actually it is an pre-assembly oil dip stick plug. The transmission is built in a different factory. It is shipped without the transmission dip stick in place. The plastic thing that looks like a fishing bobber keeps the debris out during storage/transport.
When the car is assembled, the dip stick is inserted pushing the plug into the pan.
The plug doesn't hurt anything. Simply throw it away.
Now, if you find the plug in the pan, this likely means that the transmission has never been serviced.
Does that help/make sense?
+1 I found the same assembly plug when I just changed my tranny filter at 120k miles (I know, I know - shame on me!). It's not needed.
FLASH = 98 V6, chrome yellow, black & blue accents, 146k daily driver POWER
: divorced exhaust with glasspacks; BBK CAI, TB, UDPs; (shift kit in the garage) STYLE
: black headlights, black taillights, black grille, black hood pins, black window tint, blue hood & side scoops, blue billet fuel door, interior billet, 12000k HIDs RIMS
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: BFG KDW/2 245/40R18 front, 275/35R18 rear