This is due to the addition of the Super Stock AA class which is the 5.5lbs weight break.
They changed what used to be A automotic to SSA/A. Then SS/AA is the AA class manual trans, SS/AAA is AA class auto trans.
The SS/AA and SS/AAA have 9.40 indexes.
SSA/A has a 9.70 index
SS/A has a 9.65 index.
http://www.nhra.com/competition/classindexs.aspx
I noticed Bill already answered after I posted this.