93 w124 - where's the oil filter?

[jsmith]

got through the spark plug change real easy. now getting ready for the oil change but whoa. the dealer gave me a filter cartridge (it says 104 on it) but i'm not sure where the filter housing really is. i even asked if the 2.8 had a different filter and they said no. from the DIY pages i can see something that looks like a screw-on filter in the back, in which case i have to ask - did i get the right part from the dealer? there is also something on the driver side in front of the engine which a local mech pointer at and said that's it (also has some kind of oil line attached to it). but there's a rubber knob sitting on top of it with directional arrows that don't say anything else. help!!!

ps. yeah finally got a cd manual on ebay but it ain't here yet, my dumb questions oughta lessen shortly...