Hi Troy,
There were two '08 prototypes built, both belong to Mopar.
'09 was the first year for public availability. Cars were serialized as 2009s but did have 2008 sheetmetal as well as a few other components.
The part number for a first year, 2009 drag pak was not as openly marketed as it was in subsequent years.
In 2009, the dealer would be notified their application was approved, then when the car was about to be completed they would be billed under a normal P series, Mopar Performance part number.
That all changed in later years, and the part numbers became more openly stated in the materials.
6.1 atx was P5155647, 6.1 mtx was P5155648.
Hope that helps a little