2 questions on a cv p71

THIS IS FOR A 1999 CROWN VIC P71.

1--What is the black-box-looking thing on the bottom of the gas tank
that has a hose on each side going toward the front of the car?

2--I put on a NEW alternator and everything works great. BUT when
I was checking the oil today I heard a low buzzing noise and it was
at the NEW alternator.I have 130 miles on the new one and with everything
OFF I still have the buzzing noise. The old alt did not have this noise.
THANKS FOR ANY HELP.

THIS IS FOR A 1999 CROWN VIC P71.

1--What is the black-box-looking thing on the bottom of the gas tank
that has a hose on each side going toward the front of the car?

This is the evap charcoal canister. It absorbs evaporated gasoline from the fuel tank which is then sucked into the engine when it is running. It is part of the emissions system.

2--I put on a NEW alternator and everything works great. BUT when
I was checking the oil today I heard a low buzzing noise and it was
at the NEW alternator.I have 130 miles on the new one and with everything
OFF I still have the buzzing noise. The old alt did not have this noise.
THANKS FOR ANY HELP.

I recently put on a remanufactured alternator and I have a slight buzzing noise as well. I checked voltages and everything is fine so I don't believe there is a problem. To me it's real faint and can only be detected if actually listening for it. If you can hear it loudly or with the hood closed, I'd check the battery and alternator connections once more.