My car also had both the muffler and resonator but it was one long piece with no seperation between the muffler and resonator. Unless your car has had the exhaust system replaced in the past, I would think it's the same way.

My problem was that the weld on the pipe going into the rear muffler rusted through. If I'd caught it earlier, I could have had it welded.

I paid $412.55 for all the parts from the catalyic converter back. That included shipping from California to Arizona. This was from Caliber Motors who is a Mercedes dealer that will discount parts.