JOHN A. (Junior) Gotti's almost-overnight rise to the top has gotten the ultimate law enforcement compliment: a full scale federal grand jury probe of Junior and his junior henchmen.

The grand jury is probing Junior's role in the current hierarchy of the Gambino crime family: the loansharking, protection and labor rackets he is said to control and his quasi-legitimate interests in several bars and nightclubs in Queens and on Long Island, said Gang Land sources who declined to provide specifics.

Gotti, a reputed Gambino capo since 1990, has been functioning basically as acting boss, visiting his father regularly at the federal penitentiary in Marion, Ill., and relaying orders to the other Gambino family capos, sources said.

The young, musclebound Gotti holds court every Wednesday night at the Our Friends Social Club in South Ozone Park, Queens, for the 25 reputed mobsters and associates under his control.

About a dozen young members of his crew have been hit with subpoenas by a Brooklyn federal grand jury that is headed by the same prosecutors who sent the elder Gotti away for life - John Gleeson and Laura Ward, sources said.

The outspoken Bruce Cutler, attorney for father and son, was taking it all in stride. "We're aware of the government's targeting of John Gotti's son, the way they targeted the father," he said. "If charges are brought, we'll meet them head on."

Also subpoenaed by the grand jury was John (Jackie Nose) D'Amico, (photo) a reputed capo who was a regular spectator and kibitzer during the murder and racketeering trial last year of John Gotti, the father.

D'Amico, a veteran of these kinds of judicial invitations invoked his Fifth Amendment rights and refused to testify, sources said.

Junior Gotti has not been subpoenaed and - befitting his status as a main target of the probe - won't be asked to testify before the panel.

NOT so lucky - or very lucky, depending on your point of view -- is Junior's brother-in-law, Carmine Agnello, a successful junk-car dealer/businessman who has been tabbed for testimony by the Brooklyn grand jury.

Agnello is trying to beg off, claiming that scar tissue lodged near his brain has dulled his powers of recall so badly the feds might as well subpoena one of his rusted- out clunkers for all the help he can provide.

Agnello's reputed memory problems are documented in sealed court papers filed with Brooklyn Federal Judge Eugene Nickerson, who has put Agnello's grand jury appearance on hold for the time being, the sources said.

A cynical view among some investigators has Agnello preparing a defense to possible charges of criminal contempt, perjury or obstruction of justice for trying to stymie the federal panel.

Yesterday, we tried to raise the cynical view with Agnello's lawyer, Anthony Cardinale of Boston. But Cardinale, a defense team member at the trial of John Gotti, the father, refused comment, as did Gleeeson, Ward and D'Amico lawyer James DiPietro.