I know you got the Mercedes seats. But for anyone else looking the cadillac cts seats are a nice seat with integrated shoulder belts. A set can be had for $350 bucks. Also the chrysler sebring seats are very similar. Similar prices too.
I ended up with the CTS seats. Drop shipped to my local shipper. Heavy duty seats. Just gotta figure out the wiring for controls now. Not a big deal. OH. And try to make sure the air bag is completely out of the circuit. Dont want to accidentally rip the sides of the seats out with a wrong wiring.
JR