I have tried smacking it a few times with no luck, ordered a cover with a fill plug should be here today.

That'll do it.

Got it today, sanded it, primed and painted it dull aluminum looks good, and it has a fill plug so will be set for changes from now on, has a magnetic plug and I put an extra pan magnet towards the bottom.
Mike

I know I'm late to the dance but, I've remove alot of those plugs by heating the plug (not the housing) and then cooling it with a hose (cool to the tough) add the plug removes easily. Just a thought for reference.

Good news!

Is the fill plug on the pan at the same height as the seized fill plug on the housing?

You got iy and that'* good. I would have taken the old pan off and if nothing else install a bung in it.

Yes, it is within a 1/2" of the plug in the housing so it will be fine the slinger will pick it up no problem

thought about that but found one on Ebay for $20 free 2 day shipping so i avoided the extra work

Cool!!

Another thread for the same issue on the same platform: https://www.gmforum.com/gmc-chevrole...ll-plug-314469