The 55559955 number is the current correct P/N for all variants of the iron block 4-cylinder engine. It has replaced all previous P/Ns regardless of vehicle model year.
I found your part number - finally. It was used on the 2001 - 2003 9-3 and the 2000-2005 9-5. It is an old part which if new may not work properly if it was stored improperly, and if already used it can be guaranteed to have a very short operational life.