Chris met Rick during AC/DC’ s Stiff Upper Lip Tour as their support band. His Marshall broke down and he used a Wizard and Rick made him some Modern Classic’s after that tour.
It’s a plexi on the album but he got the Wizards very soon after, mostly for touring. This is from memory of an interview I read around the time right after the album. So can’t say 100%. I saw the tour in San Diego and he was using Wizards.