The part number is A0015421317 and you just order them with the Mercedes dealer. They are ca $500 a piece. May try other places or aftermarket.
However: I cannot imagine how can they blow a fuse. They are hydraulic switches. All they do is to provide the ground from transmission housing to a green/red wire that goes from each of them to the connector on the transmission and then one green/red wire goes to the solenoid and provides ground to it so that it works. If the switches are off, no ground, no solenoid action. It would always look like "both of them" because they are connected.
If you have your fuse 5 blown, it may be the solenoid, but not the switches. Check the solenoid connection - there are wires sticking out of this solenoid housing that connect through a plastic base with the power supply to the solenoid from fuse 5 (green, red, black) and the wire I mentioned, ground from switches (red, green). Make sure the wires that stick out of the solenoid housing are not touching each other.
Also: the reverse lights are also powered from fuse 5. If there is a short, when you select R, you will blow the fuse. This involves switch on the firewall and the lights themselves to check.
