I can find no record of a 71st Tank Destroyer Battalion. Also, I can find no record of any tank destroyer battalion being formally attached to the 1st Armored Division. HOWEVER, the following may be of interest.
71st Tank Battalion was assigned to the 1st Cavalry Division from 14 March 1949 to 16 October 1950.
Constituted in the Regular Army 13 January 1941 as 3d Battalion, 7th Armor (Light) and assigned to 4th Armored Division. Activated 15 April 1941 at Pine Camp, New York. Redesignated 3d Battalion, 37th Armor 8 May 1941. Relieved from assignment to 4th Armored Division, reorganized and redesignated 706th Tank Battalion 10 September 1943. Served in the Pacific Theater; three campaign credits (Western Pacific, Leyte & Ryukyu Islands) (Company D awarded PRESIDENTIAL UNIT CITATION for action at Ie Shima in the Ryukyus; entire battalion awarded MERITORIOUS UNIT COMMENDATION for the period 25 April 1944 to 27 June 1945 while attached to 77th Infantry Division at Leyte; entire battalion awarded PHILIPPINE PRESIDENTIAL UNIT CITATION by the Philippine Government for service in the Philippines, 17 October 1944 to 4 July 1945). Inactivated 20 September 1946 in the Philippines.
Redesignated 71st Heavy Tank Battalion and assigned to 1st Cavalry Division 14 March 1949. Activated 25 March 1949 at Chigasaki, Honshu, Japan. Redesignated 71st Tank Battalion 5 August 1950. Served in Korea; two campaign credits (United Nations Defensive & United Nations Offensive) (Company A awarded PRESIDENTIAL UNIT CITATION for the period 2 July to 15 September 1950; entire battalion awarded streamer in the colors of the CHRYSSOUN ARISTION ANDRIAS [Bravery Gold Medal of Greece] and the REPUBLIC OF KOREA PRESIDENTIAL UNIT CITATION for the period 16 August to 26 September 1950). Relieved from assignment to 1st Cavalry Division and inactivated in Korea 16 October 1950.
Redesignated 706th Tank Battalion 14 August 1951. Assigned to 12th Armored Division 25 February 1953. Relieved from assignment to 12th Armored Division 1 April 1957 and consolidated with 37th Armor, a parent regiment under the Combat Arms Regimental System (CARS).
The battalion's lineage and honors are perpetuated through Headquarters & Headquarters Company, 5th Battalion, 37th Armor which is currently inactive.