Ford Repair: C4 Trans., 1978 ford fairmont, ford fairmont

Question
1978 Ford Fairmont, 302, C4. I took the pan off of my C4 to do the filter and fluid change and a plastic piece fell out of the pan when I tipped it to drain it. It's cylindrical (about 1/2" diameter) with a cylindrical 'tail' (about 1/16" diameter). Overall it's about 2" long. On the larger cylinder there's a groove with a black rubber washer in the groove. It's sort of yellowish in colour. Any idea what this is? I tried wiggling it up beside the valve body to see if it may have come down from up inside the trans., but it wouldn't fit anywhere up besdie the valve body. I can't find any place that this piece fits or looks like it came from. I'm really stumped about this piece.

Answer
Throw the plastic away - it was a plug that the factory used to block the dipstick hole prior to the installation.  That plastic plug was designed to be pushed into the pan as the dipstick is installed, and lay there harmlessly until the pan is removed for service later.  WOW - 25 years!
Clay