Help identifying part

[Froski]

So I was removing the side cover in my 3FE and this rubber plug falls to the ground under the engine.

I
had the oil pan off. It must have come from the area between the oil reservoir and the push rods right? Anyone know what it is? I searched the number on it and came up dry. TIA

 

[jonheld]

That looks like the timing hole cover. Lives on the bellhousing just above the starter and plugs the hole where you aim the timing light.

 

[Froski]

Thanks Jon,
And thanks for your continued availability on this forum for 3FE owners. In addition to the leaks on this one, I am replacing the parts from your tune up list.