The spotter had made multiple measurements of what is visible on satellite imagery, and it apparently matched up with the dimensions of the PB4Y.
Aircraft Type: Consolidated PB4Y-2 Privateer
Registration: 59777
Airline: United States Air Force
Location: Southern area of Glacier Bay Nat'l Park
Visible through satellite imagery.
There is no information about this PB4Y prior to its crash, other than its service with the US Navy.
On November 30, 1945, 59777 took off from NAS Kodiak with Seattle as its destination. It gave its last position over Sitka then disappeared. Searches from the Navy and Coast Guard found nothing.
Recently, a spotter on wreckchasing.com claimed to have found the wreckage of the aircraft. However, the topic has been deleted and it's unknown if this is truly the remains of the missing PB4Y.
(Note: A Reddit user has this site in their collection (as 'Unknown'), so I'll take that as confirmation that this is 59777)