I usually just change mounts on any Merc. that I work on.As arule you cannot see the wear on the mount until it is removed and placed alongside the new mounts.if you suspect flattened mounts ,check oil leak issues as even power steering fluid will rot rubber. look at the exhaust manifolds and see if they are close to the steering etc,dead mounts will locate your engine so that it is too close to "any thing important."