Not so fast, you give up too quickly. In fact all 96s were 722.329 and all 97s were 722.605. Put in 1997 E320 and you get the same page showing both 1996 / 1997 filters. http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1W50YN0EQ20G1BTC6A&year=1997&make=MB&model=E-320-002&category=J&part=AT+Filter

In fact it was a clean model year split - all .3s in 1996 and all .6s in 1997 - confirmed by EPA test results at: www.fueleconomy.gov - i.e. all 4 speeds in 96 and all 5 speeds in 97. Rare, but I think we've got Arthur on this one.