A lot of 4 cylinders and the Duramax 3.0L engine. The claim is that these belts reduce noise because chains are "loud".
They aren't even trying to hide the whole planned-obsolescence thing at this point. Average age of cars on the road is approaching 13 years now, so someone who buys a Duramax-based vehicle will end up with a metal and plastic brick that costs more to maintain than it's worth, just because of the timing belt alone.