Good! I got my Hardin ones too. 6 of them for $43 shipped.

McMaster Carr for cheap
Same one’s Volvo Penta andcetc use for block drains

https://www.mcmaster.com/4921K2/

Last time this happened to me couple boats back on a 502MAG, I used a bigger drill bit than the hollow hole left behind. I guess its the same as an EZ out, but the drill bit method, turning by hand, worked for me....

Do those replace the blue plastic "wing nut" in the plastic elbow?
I have the Hardin Marine SS ones and stripped the threads in the plastic elbow with one. Drained the water on a warm engine (soft plastic) and re-installed it while hanging up-side down over the rear bench seat. So it cross threaded pretty easy. This would be a MUCH better set up IMO.

What I just bought was the brass elbow with the brass nut to remedy this, but see that brass and aluminum have bad corrosion problems. This concerns me greatly as the cost of manifolds is expensive.

I do have the pencil anodes installed in the manifolds which should help, but mot sure how much? .

What I showed is two piece. The bottom has npt (national pipe thread) threads. Like what is in the engine block.