2 issues, clutch and housing cover.

Isn't there a square rubber inspection plug on bottom of bell housing, maybe could fish it out. Or maybe I'm thinking of a different vehicle....

If you look at #6 on the first picture "drive plate cover" may also be called bellhousing under cover or dust cover. The rubber seal sits on top of this. The second picture is of only this cover. The top edge is where the rubber seal fits over. You can see a faint bead of what used to be some sort of adhesive/silicone or similar material which I believe helped the rubber seal stay attached to the cover.

My rubber seal was pretty loose when I was doing an oil pan gasket change. I inspected the area a day later and noticed the rubber seal is now missing. I believe it to have went inside of the bell housing where the flywheel is located.

Bled the clutch hydraulics, all is well. Cant find replacement seal though

contact , board sponsor.

If you're talking about the inspection hole cover (rubber bit) it can be replaced easily. I doubt it "fell" into the transmission - especially since it's on the lower half of the trans. You can find a replacement on any Nissan or Mazda with that transmission. And I bet its the same inspection plug on many transmissions from other manufactures. I'm pretty sure it's the same as my 97 Ranger (a Ford) - I'll have to check it out now that I think of it.