IT was Spring, 1987, and John Gotti, fresh from a stunning acquittal of federal racketeering charges, turned his sights on mob rival Vincent (Chin) Gigante.

Gigante, however, proved a much more difficult foe than the federal prosecutors, according to Peter Savino, the FBI's key informant in the Mafia "Windows" case currently on trial in Brooklyn Federal Court.

Gotti dispatched Salvatore (Sammy Bull) Gravano to meet Venero (Benny Eggs) Mangano, the underboss of the Genovese family, to demand a fair share of the mob's millions of dollars in window-replacement contracts with the New York City Housing Authority.

Gravano, who owns several construction companies, sat down with Savino and Mangano at his Thompson St. social club and "complained that his family was the only family not involved in" the bid-rigging scheme with the Housing Authority, according to an FBI report obtained by Gang Land.

"That work is ours," said Mangano. He told Gravano to talk to Frank (Frankie Dap) Dapolito, a Gambino soldier who had supposedly agreed that the window scheme was Genovese territory.

A few days later, Dapolito admitted the agreement to Gravano, who yelled at him, reprimanded him for not checking with Gotti or Gravano, threw him out of their meeting, and then pressed his case again with Mangano.

"Dapolito had no right to agree to anything, and Dapolito was wrong to do it," Gravano told Mangano, stressing that the Gambino "family would be in the window business, no matter what," said the FBI report.

The meeting broke up with Gravano promising to speak to Gotti, and Mangano promising to speak to Gigante.

In the end, after another sitdown or two, however, the dispute was resolved much the way Gigante had wanted it all along.