I have a GM Navigaion Disc available for your tow vehicle... PM me if your interested...
Map data released as version 6.0c.

GM part # 20940248

List of vehicle compatibility:

only 2007 2008 2009 2010 2011 GMC Yukon, Sierra and Yukon Hybrids ( all models)

only 2007 2008 2009 2010 2011 GMC Savana (all models)

only 2007 2008 2009 2010 2011 Chevrolet Avalanche, Suburban, Silverado, and Tahoe (all models)

only 2006 2007 2008 2009 2010 2011 Cadillac DTS (all models)

only 2007 2008 2009 2010 2011 Cadillac SRX (all models)

only 2008 2009 2010 Hummer H2 (all models)