Cooling System and H2O Pump

'01 X5 3.0:
I have a water leak between the 'female' port on the bottom of the Expansion Tank and the "male" port that it slips over. I see that none of the O Rings are sold separately, this one comes in the tank I believe.....short of a drive around to the local auto parts stores afther I have it all apart........any suggestions? This O ring is about 1-1/2" in diameter.

Also: any DYI out there on the H2O pump replacenent? Other parts taht should be done at the same time?

Thanks in adavance.
Mike

do you have any pictures you can post of this tank?