found the interview with guitar center:
"GC: Tell us about your basses. What do you use and why do you use it?
Mike: Right now, I'm using anything from 1963 to 1974 Fender P-Basses, mostly ash bodies. Sometimes I'll swap out the pickups, if they're dying, to a Seymour Duncan antiquity, which is a pretty hot pickup. I used to use a Gibson G3 bass years ago. I played at least 700 shows out of that thing before Tre accidentally broke the neck on it twice on stage by pushing over my amps."
found here:
http://gc.guitarcenter.com/interview/greenday/