I would take it to a reputable M/B shop and have it put up in the air.

You probably have brittle fuel hoses as well as a banjo fitting copper crush washer leaking.

If you replace a crush washer, chances are you will create another leak from pinching off/disturbing the rubber fuel hoses.

If it were my vehicle, I would have (all) the rubber hoses replaced and have the fuel filter/pump package resealed with new washers.

This is definitely not a job you want to try to tackle in your driveway as it is extremely messy with the fuel that goes everywhere, not to mention extremely dangerous to do on the ground especially with those older cars and their notoriously brittle rubber fuel hoses.

If you snap a main fuel supply hose, you can be in big trouble, real quick.