Muffler hangers, although made of durable rubber, will deteriorate over time. Heat, road salts, and vibration all contribute to this deterioration. Any time you replace a muffler or any section of the exhaust system, it is a good idea to replace the corresponding muffler hangers, exhaust seal rings and muffler clamps also.
Hanger is FRONT muffler hanger on these vehicles:
1987 300TD
1988-1993 300TE
1992-1993 400E
1992-1993 500E
1994-1995 E420
1994 E500
Hanger is for CENTER on all other listed vehicles.