tranny plug

[3406E]

the canadian salt have got the best of this fill plug. heated it, tried a pipe wrench but doesn't get a proper grip, tried a chisel and nope doesn't even budge. The 1/2 inch socket kept spinning in it it because the rust decayed out the hole. The bottom plug was ok, i cracked it loose but didn't run it out because i haven't open the fill plug yet.You guys have any idea besides welding a nut on it to pull it out? thanks