Thanks, I actually figured it out today with the help of Mercedes. Apparently my dealer did not have a parts breakout showing the SRT-6 specific parts, so they had the right part all along but thought it was wrong because they had never worked in an SRT-6 exhaust before, and the illustration showed the setup for the standard model, which is very different. To make matters worse, they don't have my car so they couldn't just look and see.

At any rate I'm all set now. Also, the parts match the Mercedes SLK32 parts, as expected and I now have the Mercedes cross-reference for these. I'll post them here tomorrow after I get them off my desk at work so if anyone needs to replace them out of warranty they can just order the parts from Mercedes. They are $1,450 per side from mercedes, but $2,300 from Chrysler. The dealer did verify the matching Mercedes part numbers stamped in the side.