20/20 stands for clearest vision/eyesight, right? I think that is what they were alluding to unless it is a coded version for the sexual practice of 69 as forever commemorated by Herr Bryan Adams (no, he was not singing about the year!). But then Gibson bass names haven often been a bit silly ("Money", except that it didn't make them any!) or non-descript (all those countless number and letter combinations). Thunderbird was/is catchy. And so were Victory, Ripper and Grabber, but EB-Whatever or L-9S (originally for the Ripper)?