To all owners who have a vessel sink in their bathroom. The first picture is of the drain tube that screws onto the bottom of the sink drain shown in the second picture. Where these two meet, there is significant galvanic corrosion, so much so that the nut of the drain tube was corroded through, allowing the tube to come away from the sink drain. The bottom of the sink drain was so corroded that the compression nut that pushes the washer against the bottom of the sink to make a seal, would not unscrew and had to be cut with a Dremel to be removed.
As per Mr. Ulmer; "The part you need is made by Dehco Inc.
Replacement parts are available from Recreation Nation
https://recreationnation.me/main/catalog/169
The part is (ORB VESSEL FILLER DRAIN) the part number is 204790".
When I install the new parts, a coating of dielectric grease
will prevent future corrosion at the junction of the Sink Drain and Drain Tube.