I have an irratic tach and have run across some info stating that GM may have an extended warranty on this and all the stepper motors for that matter, but called the local dealer and they knew nothing of it. Would anyone have a bullitin # or something on this?

Dealer doesn't know anything? Yeah.

Try to find (on the web) a copy of:

Technical Service Bulletin 07187C, issued March 2009. Campaign - Instrument Cluster Warranty Extended

Even if you can't find a complete copy of the TSB, again approach the "I dunno" dealer and suggest they check their records for this particular document, which they must have "overlooked".

Can't guarantee that you/your vehicle are covered, but check it out. At least GM acknowledges that there's a problem even if your dealer doesn't.