With some changes in my google searches I think I figured this out and that it is a dipstick shipping plug. Leaving this up in case it helps someone else.
Here is the question I found:
I have an '85 F-250 4x4 {460cid, C6, B/W1345} and I dropped the tranny pan today to change fliud and filter. When I got the pan down there was this funky plastic "thing" in it. It appears to be off-white nylon and it looks like huge hollowpoint bullet {approx 5/8" in diameter} and there's a rubber ring around where the crimp/lube ring would be on a bullet {yes..I know more about reloading than I do about auto trannys} and lastly there's a post sticking out of the base of the "bullet" that's approx. 1-1/8" long and maybe 3/16" in diameter. The whole thing is one solid piece of nylon {except for the O-ring} What in the heck is that thing??? I looked all around the valve body and can find no obvious place where it'll fit. Is it supposed to be there or was it beamed there by aliens? Any help would be appreciated as I cannot reassemble the darned thing until I know what it is?
Here is the response:
Does it look like it would fit in the hole where the trans fill tube/dip stick is? It could be a shipping plug that is used to fill that hole until the dip stick is pushed in to the trans during assembly. The part sticking out would be used to grab ahold of and remove the plug. The o-ring would seal the hole for shipping. If the assembler did not remove the plug and just pushed in the dip stick, the plug ends up in the pan until the fluid gets changed.