For 2003-2006 models having a 50/50 3rd row bench, the tether anchor for 3C could be used instead for 3P – but never for 2 car seats at one time!
For 2007-2014 models having a 50/50 3rd row bench, the tether anchor for 3C could be used instead for 3D – but never for 2 car seats at one time!
See above that the late-2002 Suburban has a different arrangement for the lower anchors in the 2nd row.