Zakk Wylde in an interview looking back on No Rest for the Wicked, said that they recorded the whole record with the first producer. He said, the tone was really weak and the mix was more AOR. He recorded that version with the Lee Jackson Metaltronix stuff. He complained to Ozzy that it wasn't heavy enough. Ozzy said, tell him. He said, that he went to the producer and said, we need to redo some parts. The producer said, which ones? Zakk said, all of them. The producer threw his stuff down and walked out. They fired him.
They then went to Keith Olsen, who had just come off of Whitesnake. Zakk said that he played him, Dokken Under Lock and Key, Ratt Invasion and TNT Tell No Tales and said, this is the sound I want. Keith pulled out a JCM 800 combo and said, this is what I recorded John Sykes on, this is the same setup. So he retracked the entire record and that is what you hear on it. I always assumed it was the Mesa, but perhaps it's multi tracked with the 800 to give it more high end sizzle.
You can tell they still kept some of the Lee Jackson tracks, Crazy Babies being one of them, as the tone is a little different.