The Reagan administration came through yesterday with a pre-election plum for Rep. Joseph P. Addabbo (D-N.Y.), the lawmaker now in the best position to help or hurt President Reagan's defense budget.

The Navy announced that it was awarding Coastal Drydock Repair, located at the old Brooklyn Navy Yard, a $40.7 million contract to overhaul one of its fast frigates, the USS McCandless, with options to do two others later.

Addabbo, chairman of the House Appropriations subcommittee on defense, had complained strenuously to Navy Secretary John F. Lehman Jr. and other Pentagon executives when Coastal Drydock did not get the contract to recondition the battleship Iowa, which is being taken out of mothballs as part of Reagan's plan to rearm America.

"They towed it right out of his district," said Sen. Ted Stevens (R-Alaska), chairman of the Senate Appropriations subcommittee on defense, in warning that Pentagon leaders "have to find a way of getting him to cooperate" if they expect their fiscal 1983 money bill to get through Addabbo's subcommittee in good shape. "Right now," Stevens commented regarding Addabbo's role in shaping the defense budget, "he doesn't have any real motivation."

Pentagon executives agreed that Addabbo is the biggest obstacle to the defense budget, which has cleared Stevens' subcommittee but not Addabbo's. They also said they had felt his anger about some recent contract choices.

Asked if he thought he had received fair treatment at the hands of the Pentagon recently, Addabbo said "no." However, he said this is not why he will try to cut out two nuclear-powered aircraft carriers as part of his effort to reduce Reagan's defense budget by $11.5 billion.

He said that the cut is needed to squeeze the budget under the congressionally imposed ceiling, and that the aircraft carriers, costing $3.4 billion each, would not be a sensible investment for the country.

Although Addabbo represents part of Queens, not Brooklyn, his home area is expected to get an economic lift from the big contract awarded to Coastal Drydock Repair.