Please Help!!!

My car is a 1992 LeSabre. I'm not exactly sure what the specific hose is called, but may be Thermostat Bypass hose, or maybe just Bypass Hose. It's mounted on the top of the water pump and screws (via a plastic attachment) into the block. The only thing I'm 100% on is that it is a water hose.
Anyway, the plastic screw-in attachment broke off flush with the block, so now I have melted plastic in aluminum threads. I'm prepared to re-tap the threads if necessary. Hopefully there's an easier way to remove the melted plastic.
My worst problem though, is that I'm having trouble replacing the melted piece because I don't know exactly what it's called.
Has anyone encountered this melted plastic problem? What should I try?
What's the attachment called?
Thanks.

Bypass nipple

If you can locate an easy- out large enough to fit in the hole, the broken off piece will screw right out.
Otherwise you can take a hacksaw blade and cut the plastic and break off the pieces.
GM parts has a metal replacement available.

Thank you GMMerlin!