Identify this part in transmission pan

I found this in my trucks transmission pan when i dropped it down to change the fluid. It looks like a pressure regulating plunger or somethin

I thought maybe some one here may recognize it.

It's a '03 F-150 with the 4R70 (same as a E4OD - I thinK)

Oh yeah, it shifts fine and has for the last 30K miles. I think maybe it has been there since it was put together.

Thanx

Nevermind. I got an answer at F150online Forums:

"it's a plug from the dipstick tube. The trans is built without a dipstick, and that plug fills the hole. At the assembly plant the dipstick is pushed into the trans and the plug falls into the pan."