[3] USS Passumpsic (AO-107) was laid down on 8 March 1945 as Maritime Commission Hull 2703 by Sun Shipbuilding and Drydock Company, Chester, Pennsylvania.

Upon return from deployment in April 1964, Passumpsic underwent an INSURV Board inspection at Long Beach Naval Shipyard in preparation for "Jumboization," a project of modernization and renovation for Mispillion-class fleet oilers.

At Boston Naval Shipyard a Supply Overhaul Assistance Program (SOAP) was set up to sort, identify, and repackage the ship’s stock of repair parts and to receive, sort, and stow the repair parts supplied by the contractor and the U.S. Navy in conjunction with the conversion programs.

After passage through the Panama Canal and St. Lawrence Seaway, Passumpsic was placed "in commission, in reserve" on 26 November 1964 and most of her crew detached, leaving a nucleus party of four officers and 28 enlisted men under the command of Lcdr.

Passumpsic departed Norfolk on 11 March 1966 for her home port of Long Beach, California, arriving there on 6 April 1966.

Final U.S. Navy acceptance came on 24 August 1966, and she was designated a ready unit under Commander Task Group 13.1 (CTG 13.1) on 1 September 1966.

She returned to Long Beach 27 June 1969 for yard availability, local training operations, and preparations for her next Western Pacific deployment.

She transferred to the Military Sealift Command on the same day, becoming United States Naval Ship USNS Passumpsic (T-AO-107).

Passumpsic was in Subic Bay at Luzon in the Philippine Islands when Mount Pinatubo erupted in 1991, suffering extensive damage to her Underway replenishment (UNREP) gear caused by a mixture of volcanic ash and rain water from a passing typhoon.