Removing Brake Hoses

[Zilverado]

So I'm looking at replacing the rubber brake hoses on the front of the truck. Besides bathing everything in penetrant and using proper flare-nut wrenches, is there a trick to separating the rubber line from the rigid line where it goes through the frame rail? Do I need to use a wrench on the backside (inside) of the frame rail as well, or is this connection held in place by the frame somehow (welded, clipped, etc). I took a real quick look the other night, but couldn't really see back there too well.