My 2000 F150 drifts when in park and you can hear a noise while it is drifting.

GET SHIFTER SYSTEM CHECKED SOUNDS LIKE PARK PAWL NOT PROPERLY ENGAGING. USE PARK BRAKE WHEN PARKING!

When you put your vehicle into park it may roll or drift a bit until the parking pawl inside the transmission engages itself. As it does this you may hear noises from the pawl as it springs into place. This is a normal condition for automatic transmissions. Make sure you set the parking brake once you place your gear selector in park especially on hills to alleviate the pressure put on the parking pawl by the weight of the vehicle.

there is a detent in your transmission that may be a lil off causing a drift...you need to have someone adjust this detent....