I have done it on my 85 380SE. It just slips (pulls) straight out after some bolts are removed from underneath and the rear seat back is removed. Just peel the carpet off and reattach - you can buy matching fabric at a fabric store and use 3M super spray adhesive to bind. Should only take you 2 or 3 hours.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280