How in the blang dang m-f'in do you get the tube nut loose while the motor is still in the truck?

I can't get anything in there to loosen the nut. Tried taking off the nut at the manifold,,,but the fitting started coming out and I can't fit any wrenches in that tight-a$$ space either....

 

So, does anybody know what the nut size is?

I'll buy a line wrench crows foot and try that...

 

Use PB-Blaster all over the nut and you should be good to go.