[C320-list] Fuel gauge sender ground

[mike hunter]

Hello,
   
  I’ve narrowed my inoperable fuel gauge down to the grounding of the fuel gauge sending unit.  The ground wire is currently connected to one of the bolts extending down through the deck from the diesel deck fill plate.  Is this the typical location of the sender ground?  Is there another / better location to ground to (I’m having a tough time finding ground back there)?  I was told not to ground to the chain plate bolts passing through the transom, is this true?  
   
Thanks!