EDIT: I clicked the send and then found out seems I'm late for the party

2006 MY got S350 SWB, other model years were all LWB models without L in name.

2000 MY
https://web.archive.org/web/20000229092558/http://www.mbusa.com/servlet/ModelsSe- rvlet/specs/S430V.html#anchor1
https://web.archive.org/web/20000302120442/http://www.mbusa.com/servlet/ModelsSe- rvlet/specs/S500V.html

2001 MY
https://autocatalogarchive.com/wp-content/uploads/2019/01/Mercedes-Clase-S-2001-USA.pdf

2003 MY
https://autocatalogarchive.com/wp-content/uploads/2019/01/Mercedes-Clase-S-2003-USA.pdf

2004 MY
https://xr793.com/wp-content/uploads/2024/03/2004-Mercedes-Benz-S-Class.pdf

2005 MY
https://www.cars.com/research/mercedes_benz-s_class-2005/specs/#research-trim-specs

However, a SWB S350 was offered for 2006 MY
https://drivingwithscissors.com/IMAGES/MB3/200620S-Class20Guide.pdf