A while back I bought an old Gibson SB-450 bass with a broken truss rod. Rather than remove the entire fret board and risk the neck deciding that it didn't like the way it was shaped and doing some gyrations that would necessitate more work, I'd like to just remove the portion of the board that covers the end. Remove a fret, saw through the board, remove the small end section of board, cut off the anti-rotation device, insert new rod through and fix a new rotation stopper. Then replace the fret board, fret and do a level and dress. Similar to this -https://www.youtube.com/watch?v=579yVhMua5Y My only question is how long is the rod? I'd like to not remove any more of the board than I have to, but at this point it would be a by guess and by gosh on my part. Anyone have any knowledge to share on this?