Sorry I misunderstood.

I can't imagine what would be there for those plugs. Three or 4 inches from the oil drain plug, in any direction (i.e., radius of a circle) around the drain plug on a red-block engine sump is virtually in the middle of nowhere! There should be no other hole in which to put a plug. And you say that there's also one on the transmission (automatic?) sump, too?

It would really be helpful if you had a picture (digital camera?), but let's try anyway to think out-of the box -- this is certainly *not* factory equipment! So here're two "way out there" ideas:

1) Could the P.O. (previous owner) have installed temperature gauges for the engine oil and transmission fluid? I know that the usual way is to insert sensors that substitute for the original drain plugs, and even though the better location would be the side of the sumps (to avoid being hit and broken off by road debris) maybe he wanted to install them differently, by drilling new holes so they're separate from the drain plugs. Later, he removed the senders, and filled the holes with these plugs. No? Well, I told you these would be "way out there" :-).

2) Maybe they're not plugs at all? Not being able to see what you're seeing, I'll take the liberty of suggesting that maybe they're just glued on to the bottom of the sumps, and perhaps just look like plugs. I know it's intimidating to try to remove them (and risk having your fluids drain out), but is there any sign of anything else having ever been installed? I'm thinking maybe some sort of customized skid plate that covered or extended to not only the engine sump but also the transmission? And he put some rubber cushions or "bumpers" between the sumps and the skid plate for extra impact protection? Well, as I already wrote, these are "out of the box", but what else can we do with something that shouldn't be there. And, I can't see what you're looking at.

Good luck. And think about borrowing a camera?

And Happy Thanksgiving.