75 Dart Swinger Transmission to Radiator lines wont come off

Heat always works for me

MAP torch?
Because that's what I'm gonna use.
Thanks, I don't know why this thought process didnt occur to me.
Does the big nut unscrew seperately from the plug screw?
I can't get that figured out. I'd cut it if could.

I have had that happen to me. I had to use 2 wrenchs, 1 to hold and 1 to turn.

Tried that, it's either turning the whole line, or both the plug and the line. If I try to hold it, the plug's bolt pattern starts to strip.
Sad day. Ima try the MAP torch.