The bass solo starts at 6:30
Envelope filter used through out in places and from the beginning of the solo. The 'chorus' he uses sounds like Jaco chorus to me, and given the time period, I'm thinking it's an MXR Digital Delay doing the chorus work. The overdrive is probably his amp Im guessing... and I don't hear any octaver- I think the doubling Mutt is referring to is the digi delay. That my best guess anyway.
edit-
Here's another video of them playing in Norway the same year- you can hear the bass player really playing the sh.t out of an envelope filter around the 6min mark during his solo. I was thinking FX25 but they weren't out for another year or two after... Sounds good whatever it is.