I am working on an 1978 M20J.  The avionics master relay is defective.  I am told there are no replacements for the relay I have installed.  The part number removed is 89CQX-2.  I can't find this part number anywhere.  A mooney shop gave me  the part  number of W89CQX-2.  Does anyone know where to get this  part  new or what to replace it with? Thanks, Steven