You probably have this covered,but when tightening a flare fitting,it'll sometimes set off to one side a little,and that makes it leak. I run it down very gently,and wiggle the tube as I tighten it;I can feel the tube "find center" as I go-the nut will "free up",that is it'll "loosen" a little each time I wiggle the line. When it stops freeing up,go ahead and tighten it. I haven't had one leak,even old/worn lines,in many years.
If you don't mind my asking,how much is it costing to put together a 1-1/2 or 2 Ton disc Brake set up? That's something I'll be seriously considering once I get the Cummins/NV4500 installed in my truck.
Speed


1954 GMC 350
1957 GMC 1/2 ton
1962 Chevy C-30
1952 Chevy 6400 dump bed project truck
'98 Harley FLSTC
'66 Pontiac Catalina
'76 Chevy 1 ton Duallie
'84 Bronco II
'78 Dodge W-200
'81 Toyota 4X4 truck