heres a cool thread with flemming answering questions, he a little vague on a lot of things though..
https://gearspace.com/board/so-many...e/908069-master-puppets-guitar-recording.html
"The numbers for the cabs are serial numbers as we had about 12 cabs in the studio at any given time, and Yes they do all sound different."
"As for the amps. We just used what sounded best on any given day."
It's been long rumored that on "Master of Puppets," you guys ran the Mesa Mark IIC+ head unit into a Marshall JCM 800 as a power amp. Is there any truth to that?
"Yes - we did a lot of stuff like that. So YES is the answer."