If you go back and read the interviews with Lynch during those days, you find he was a serious tone hound. He hunted high and low for the right tone. He endorsed Randalls, but was a diehard Marshall user. He rented a modified Marshall that he fell in love with and mentioned in several interviews.
"Upon returning #39 to S.I.R. following his rental of the amp, George finally learned the name of the mystery modifier who had performed the modification to #39: Tim Caswell (Tim had worked in S.I.R.