I have an old Heddon fiberglass fly rod my dad bought I think in the early to mid 1960s. On my rod the line weight is marked "H". A coworker is a fly rod guy, and has a newer rod. The line weight on his rod is marked as "6". I've made a bet with him. He claims that fly rods were marked with a letter for line weight well into the 1980s. I say he's wrong. I say the letter for line weight stopped by 1970, and changed to a number system. I really don't know a lot about fly rod fishing . For the fly fisherman here, what's the correct answer?