thks for the reply DG, you saved me from having to do it 2x... I had decided which way the filter was supposed to go in... and it turns out it was upside down.
For anyone else who reads this, if your pump still has the old school (cork?) filter ring, I believe you want to ditch the ring, the metal base and the upper plate when you put in the new filter.
BTW-my pump doesn't have the plastic piece or the nut.
thanks again, I'm sure my benz would be a smouldering wreck on the side of the road w/out this forum and its members.