I'd read that before. It's pretty interesting. Gene did nothing much at all in the non-makeup era. And yep as Wrathy said, Ace played all the lead guitar up till '78 except for those tracks on Alive II and Sweet Pain besides a couple of tracks where Paul shared the lead with him.
Interesting story about "Exciter". Vinnie played the original solo on that, then the band got the other dude in behind his back and recorded the alternate solo to use and Vinnie didn't even know at first. He was mighty pissed off when he found out too.
Jean Beauviour does heaps on Animalize. He's a champ and an awesome singer too.