I got the lines for my 69 3/4 ton from The Right Stuff at the link below.. Great people to work with. One was bent wrong, and they made one to match the one I'd removed at no charge.
http://www.getdiscbrakes.com/
Another manufacturer is Inline Tube. I've heard good things about them also.
http://inlinetube.com/
Any that you buy will generally need to be tweaked a bit.