Thanks for the advice gents.

I do think the E53 air springs are side-specific, or at least Arnott sells them that way.

The leak is from the fitting where the lower hose attaches to the radiator. slow drip on my driveway that I've had it with. My plan is to work my way around the motor and replace the big ticket hoses that are all 2002 original before they demand replacement. It seems that the radiator has plastic sides, and I'm sure the inlet and outlet are plastic as well.

For years (longer than the lower hose has been leaking) the car has lost coolant to the tune of roughly half to 2/3 of the reservoir each month. Some of the fittings do build up crusty residue, which makes me wonder if I have coolant/steam venting slowly.