Yes, there are two nuts on the edges of the filter housing and they are fine. Its the center bolt (my 123 does not have it but the 124 does) is what is stuck. I've tried to use vice grips but cannot seem to get it to bite hard enough to keep it from slipping also.

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81 300D N/A 130K miles (Nelly)
87 300D Turbo 80K miles (The Scalded Dog...because it runs like a scalded dog)
95 e320 Wagon 104K
2003 Sprinter 47K miles.
1999 Tandem Bicycle
One beautiful low miles wife (who likes diesels) (that's my wife holding the sign)

My son and I fixing Nelly's odometer