AlbanyMayor Kathy Sheehan has struck a tentative deal with the city's firefighters to keep Ladder No. 1 in the South End open in exchange for the union's help with finding $1.2 million in overtime savings elsewhere in the department.The deal is centered around the union leadership's support for a change to the firefighters' contract that would reduce the number of firefighters allowed to take vacation on the same day from 12 to eight.That change alone would save the city about half the $1.2 million target, Sheehan said, but it still requires ratification by the members of the Albany Permanent Professional Firefighters Association."We think that's a pretty conservative estimate," Sheehan said, standing side by side with union President Bob Powers at a City Hall news conference.