That's the problem with relying on your manual. The
5068 can be jacked to well over 90mm^3 with the right programming.There's a reason why we track them down and have them rebuilt.
Yeah, I know, why isn't it in the book? Probably for the same reason that the PMD issue wasn't in the book, or the same reason why the crushed downpipe wasn't in the book, or the inner-wall delamination of the crossover wasn't in the book, or...
Book is one thing. Experience is quite another, sometimes. That's why I love this place - lots of guys with all kinds of experience who like to share and learn.
If the books had it all, then the GM techs would be at least partialy reliable at fixing these trucks. And they aren't.