It only leaks when you have the faucet open, water is flowing, correct?
Then that does not seem to indicate a leaking pipe or fitting that is feeding the faucet.
Rather somehow the faucet is leaking after the faucet valve is opened up.
And just to add other possibles the sink drain, have you looked closely at the drain pipes and fittings? Maybe close or block sink, fill up some water look for leak, then open drain and look again.
2005 Dodge Ram 2500 5.9L 6 Speed
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