The Division Air Defense gun (Divad) was supposed to protect U.S. tanks by shooting down enemy planes and helicopters.

But Defense Secretary Caspar W. Weinberger, after sinking $1.8 billion into the program, canceled it in August. He said Soviet helicopters could hover beyond Divad's range and still blow up U.S. tanks with missiles, so Divad was not worth $6.5 million apiece -- three times the cost of each tank it was defending.

The program began a decade ago, when the Army decided to replace the aging Vulcan gun. Five companies expressed interest.

General Dynamics Corp. and Ford Aerospace & Communications Corp. won two-year contracts to build prototypes. After a competitive "shoot-off" in 1981, Ford won the job.

Ford and the Army named their new gun after World War I hero Sgt. Alvin York, but the gun system was more commonly known as Divad. By this summer, 65 of the planned 618 Divads had been delivered.

Its twin 40mm fast-firing guns were to be guided by a radar adapted from the Air Force's F16 fighter jet and a modern laser range finder, all mounted on an old M48 tank chassis. Divad went into production before testing was complete, an approach the Pentagon calls "concurrency."

But its guns jammed and its radar picked up false targets. Ford and the Army said the problems could have been fixed, but Weinberger -- in the only major weapon cancellation of the Reagan years -- said no.

The Army is looking again for a system to replace Vulcan.