I'm replacing driver's side brake line. Hose and the metal line.
I need a plug like this -->

Dorman AutoGrade Brake Line Plug - 785-452

But the parts stores here either don't carry anything like this, don't know what this is, or in one case, deny its existence.
I was hoping to find something like today or tomorrow but that thought seems to be slipping away.

My questions - Does anyone know what size I need to order? I hate to order something, have it come in, then it's not what I need, have to wait a few more days.

I just need to plug it while I change the brake line so all the fluid doesn't leak out.

 

The correct fitting size is M10 x 1.0 Inverted Flare Nut; Line Size: 3/16
Cut and bend the old one shut while you make up the new line. Or just drain it, you're going to bleed it either way.