You will need a Torx E14 socket to remove bolts from floor brackets. They do fit when rotated 180 degrees. The three-seater benches will install facing backwards.
For our North America market, MB designed the three-seater benches with an offset towards the drivers side to create the passageway from the slider door to the rear bench seats. When a three-person bench seat is turned to face backwards, the off-set is moved to the opposite side of the van, which can create clearance problems. Unsure if this is the case with passenger van destined for other countries, where slider doors may be located on the opposite Side.
When a three-seater bench is moved directly behind the drivers seat facing backwards, both the reclining seat feature and walk-through front seats feature are obstructed. Furthermore, the headrest nearest the slider door may come in contact with the passenger grab handle on the "B" pillar.
When the center-most three-seater is facing backwards, the passageway to the rear-most four-seater bench is obstructed. A passenger could squeeze by on the driver side, where a gap has been created.
When a four-seater bench is removed and a three-seater bench is moved to the rear-most four-seater location (facing forward), a passageway to the rear cargo area is created but one must also step over the wheel well hump.