If I recall correctly, the plastic covers on the front of the floor rails will come off after you remove the front mount bolts. Be careful about forcing them. I broke one the first time I tried taking them off.

Also, if you do get the seat completely out of the car, be careful on reinstallation that the black sliding rail fits into both the front and back of the sleeve mechanisms. It is possible to get the seat back in and have the sliding rail only go through the back sleeve mechanism--not the front too. You will damage the plastic coating on the rail when you move the seat back and forth with the motor (ask me how I know).

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles