2006 C55 AMG electrical fuel pump.
You will also need a wiring adapter from 3 to 4 wire or vice-versa (I don't remember) since that has changed. It used to come up with the pump on their site - you might want to call them. I changed out both sides about 4 years ago. It's a pretty easy job.
If you want a cheaper alternative, they have the actual pump motor for around $110.






