Soaked it in PB blaster. 14mm hex will just spin. I hammered in my 1/2 drive and that started slipping. I stopped because I didn’t want to completely destroy the threads. Thinking of hammering a 15mm in and trying to remove it that way. I don’t have a torch. Any suggestions?
You'll have to replace it anyways so maybe try vice-grips on the outside threads but it may just chew through the threads. I would buy a cheap propane torch and heat it first, it will probably come in handy later anyways. A large ez-out/screw extractor might fit in there but it may be too shallow. You could also grind a hex pattern into the outside and hammer a socket onto it. If you have access to a welder at all you could tack a socket onto it.
If you aren’t able to weld on a socket you can try jbweld as well. Either way I would def pick up a 30$ propane torch at your local Home Depot and heat it up for a quick minute, it really works wonders.
If you don't need to drive the car I would suggest taking the cover off and soak the nut and cover in rust penetrant for about 3 days.. Just spraying it isn't getting down deep enough to remove the rust so you can get it loose, Or order another and just replace the whole thing. You can probably find one in the local junk yard cheap.