If Bob has a headliner that is already installed and the headliner is already pre-drilled on the driver's side, your technique is excellent, Denny. If Bob's cardboard headliner is not pre-drilled for the driver's side visor (my cardboard headliners came with no holes for visors on either side), he would have no pattern to transfer to the other side.
Every A-D and ND cab I have seen (regular cab and panel body) was pre-drilled for visors on both sides (in the sheet metal above the pillars).
