There are two Service Manuals that I don't have access to, 2010 and 2012. However, the 2009 and the 2011 Service Manuals have the same specs as listed in Post #2. There isn't any mention of the engines or cab configurations in any of the spec listings. the chart just uses the five "Suspension Options"
-4X2 w/o RPO ZQ8, Z71
-4X2 With RPO ZQ8/QDG (18' tire) *Specs listed above.
-4X2 With RPO Z71
-4X4 With RPO Z71
-4X4 w/o RPO Z71