I had this problem at the rear of the 300SE.

Take the back rest seat out and then you might want to have strips of leather which you shall then cut into size. Insert the strips of cut leather and glue it onto the base of the seat with the leather hide facing out. This takes the squeak out of the seats.

Replace. And all should be well.

__________________
... Kerry

126 tailed by a 203, 129 leading the pack.