Hi
Try the term line wrench.
They look like a box end,with a slot cut thru the box end so the metal brake line will slip thru.Some times the small fitting on the brake line will be siezed to the metal line so be carefull when starting to turn the small fitting.If it is siezed you will have to get the bulkhead fitting loose from the frame,then you can turn the old rubber hose assembly instead of the small metal fitting.After you have the old rubber hose assembly off then you can ussally work the small fitting loose from the metal line,you have to be very carefull you dont twist the metel line .
If you can't get a line wrench and you still cant get the small fitting loose,then you can still get er done by getting the bulkhead fitting loose,using a wrench or visegrips if the small nut is getting striped hold the small fitting while turning the large fitting.
You should be able to break the jamb nut off the bulkhead fitting,they are usally stamped tin and will brake off easyly,then you should have enough play in the line to pull it thru the frame and work on it where you can see it.A big screwdriver or small prybar driven between the frame and jamb nut will usally get it loose or break it.I usally end up doing it this way ,mainly to get the small fitting and line out where you can see it and make sure you don't twist off the metal line.
Hope this helps
Thomas
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews