I think there is a thread on this somewhere.

If you already have the oil pan off, it is a good time to thread the two lower mounting holes on the bottom of the timing cover. If yours is like my 261, the bottom two bolting mechanisms are a nut & bolt. The nut being on the inside of the engine. If you thread those holes so you can use a bolt to secure the cover from the outside like the rest of the cover, you don't need to remove the oilpan to remove the timing cover.