Used m156 intake manifold. Came off a 2012 c63 with 87000 miles.  No check engine lights, no power issues, no intake leaks.   Car ran just fine.   When removing intake noticed bank 2 front tower where fuel rail bolt down starting to split.  Also crank case vent that bolts to back of intake broke off.  That was drilled out and has a steel time sert installed.   See pictures for details and questions please pm me.