On 18 August 1966, Coughlan was named at centre-back when Cork faced Kerry in the Munster final. In what his last game for the Cork under-21 football team, he ended the game on the losing side after a 3-08 to 0-14 defeat. By this stage Coughlan had become a dual player when he was also selected for the Cork under-21 hurling team. He won a Munster Under-21 Championship medal in that code on 8 September 1966 when he lined out at right wing-back in a 5-12 to 2-06 defeat of Limerick in the Munster final. Coughlan retained his position on the starting fifteen for the 3-12 to 5-06 All-Ireland final draw with Wexford on 2 October 1966. He was again selected at right wing-back for the replay on 23 October 1966, however, the game once again ended in a 4-09 apiece draw. Coughlan was switched to left wing-back for the second replay on 13 November 1966 and claimed an All-Ireland Under-21 Championship medal at the third attempt following a 9-09 to 5-09 victory.