Sorry, the NHTSA has not posted this TSB document yet.
You can still get the detailed info from Chevrolet for this TSB. Call your local Chevrolet dealer's service department & ask for a copy of TSB# SC-11150.
Affected Component: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:MANIFOLD/HEADER/MUFFLER/TAIL PIPE
GM SERVICE CAMPAIGN: SEE DOCUMENT SEARCH BUTTON FOR OWNER LETTER. 2008-2009 TRAILBLAZER/ENVOY. THE VEHICLES MAY DEVELOP A CRACK IN THE EXHAUST MANIFOLD. IT COULD RESULT IN INCREASED EXHAUST NOISE. *RM
