Experience

... But that sounds more like extreme processing with pedals and "normal" studio gear. Super-drive pedals like the Prescription Electronics Experience pedal were used quite a bit in that era, and now there's lots of similar pedals out there. Probably was not a mic'd up amp, and probably not an "amp sim" like...

...from a sine into a square wave by the distortion on a pedal - might have been the Prescription Electronics Experience pedal, might have been a vintage Fender Blender, might have just been a $99 DOD pedal, can't quite remember. I had a lot of pedals... still do actually. I recorded a few passes,...

Great question but it's tough to choose just one. With a foot pressed to the fire I'd say my fav is the Schroeder Blister Agent, 2nd is probably the BJFE EGDM. If we're getting into fuzz pedals I'd add the Cornish P1 and Prescription Electronics Experience.