In 1974-1975 they managed to qualify for the playoffs beating Club Leon 1-0, but fell to Toluca, who went on to become the champion that year.

In 1982–83 the team managed to return to the top category after defeating Deportivo Zamora in the promotion play–off.

[2] In 1997 Unión de Curtidores returned to Mexican professional football when it was registered in the Primera División 'A' (second tier), the club was registered as an affiliated team to Club León, the city's main team and its former historical rival.

[3] During the decades of 2000 and 2010 Unión de Curtidores had a presence in the Segunda and Tercera División, with representative teams that appeared and disappeared constantly.

Ten years after its last disappearance, in July 2024 the team tried to return to professional football with the help of Club Cachorros de León, even the team's management announced its return to the fields,[4] however, finally the Liga Premier de México did not authorize the move, so Curtidores attempt to return to professional activity was frustrated.