Rickenbacker basses are a daft candidate for 5-strings anyway. What next, 5 string Hofner Violin basses? If Rickenbacker redesigned the 4003 from the ground up for 5-string configuration then fair enough, but I wager they've simply tacked on another tuner, filed the nut with 5 slots and stuck 5 saddles on the bridge. Maybe jimmied 5 poles onto the pickups as well.