Received this in the mail yesterday from The Garden City Group INC:
Starts out:
TO: All California owners and lessees of 1999-2003 Chevrolet Silverados equipped with 4.8 5.3 6.0 or 8.1 L engines
...
It has to do with that knock ping or slap noise on cold engines that goes away in a few seconds (I get it on mine). The suit claims GMC's unspoken "Engine Knock Noise Adj Program violates California's Secret Warranty law.
They have a web site: girardgibbs.com/silverado