The rumor was that a relatively unknown singer Don Dokken did the 'scratch tracks' for whatever album the Scorps were recording at the time (Blackout?) while Klaus was recovering from throat surgery. They're probably demo quality at best. I don't believe he ever sang with them live or anything like that.
Don't know if any of those tapes ever surfaced though.
EDIT: yea, what that guy above me just said.
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I used to be with it, but then they changed what "it" was. Now what I'm with isn't it, and what's it seems weird and scary to me, and it'll happen to you, too.