Three-way catalyst location - GF49.10-P-3002-03GA

Model 463 

Illustrated on right side of vehicle. 

The exhaust system on the left side of the vehicle is symmetrical to the right side of the vehicle.

Fig 1: Identifying Firewall, Underfloor Catalytic Converter And Rear Muffler (Main Muffler)

Courtesy of MERCEDES-BENZ USA