The M-112 supercharged hand built engine in the SRT6 has AMG stamped into the super charger. Simply pull the plastic cover off and take a picture for the advertisement.

Most of the suspension and drive line is AMG as well. The vehicle was built in the Karmann plant so it is 100% Mercedes built using mostly Mercedes parts with some sprinkles of Chrysler for fun.

You could also take a picture of the engine bay and then find a SLK32 AMG engine bay and put them side-by-side. This will cure any 'fraud' claims.

Good luck!