Talk about a Y2K countdown.

The Clinton administration reported yesterday that only six of the government's 6,175 "mission critical" computer systems await Year 2000 certification before year's end.

"We have done our job, we have met the deadline," President Clinton said in a statement announcing the release of the last Y2K report from the Office of Management and Budget (OMB).

The report said federal agencies also had wrapped up work on 97 percent of the secondary systems that had been deemed less vital to government operations and fixed 99.6 percent of systems that exchange federal data with states.

OMB estimated the government would spend $8.38 billion on the so-called millennium bug between fiscal 1996 and fiscal 2000.

Yesterday's report listed eight systems as not ready for Y2K, but two were certified as fixed shortly after OMB distributed its report, officials said. Y2K problems involving the last six computer systems will be resolved before New Year's Day, and none of those involve serious national security or public safety issues, OMB said.

In one of the remaining cases, the Year 2000 computer glitch does involve the Army's Abrams M1A2 combat tanks--but only their clocks.

The Army owns about 500 of the tanks, which carry an internal clock calendar. Software repairs to the last 10 tanks should be completed by Friday, the Army said. Each software change takes about four hours.

"It shows what detail people are going to to make everything Y2K compliant," an Army spokesman said.

The other Y2K problems involved a classified intelligence system scheduled for retirement this month, a classified intelligence system still undergoing testing, and a Defense Department "wing command and control system." OMB said a "work-around" has been fielded for the wing command system, and anyway it will be replaced by another battle management system next year.

Two systems, handling administrative chores for the Justice Department's tax division and the Drug Enforcement Administration, also await Y2K readiness certification later this month.

In the report, OMB also sought to allay any public concerns about the Y2K readiness of the nation's aviation system.

"It is worth noting that some critics have commented that the air traffic control system is not ready, because it hasn't completed all its testing. This is not true," OMB said.

The report noted that the Federal Aviation Administration finished its Y2K work in July and "since then, the FAA has undertaken additional testing in order to provide added assurance."

In addition to federal agency efforts, OMB has tried to track repair efforts in the states, which administer a variety of federal programs, such as Medicaid, heating assistance, child welfare and disaster relief. The report listed Alabama, American Samoa, Guam and the Virgin Islands as running behind schedule on Y2K repairs.

Administration officials said public housing authorities in large cities have completed their essential Y2K fixes, but noted that it has no survey data on the progress of smaller authorities. As a result, OMB assumed in the report that some small housing authorities could face breakdowns in heating, elevator, fire and security systems during the first week of January.

The Year 2000 problem involves computer systems that use two-digit date fields and may misinterpret "00" as 1900, not 2000, causing them to malfunction or shut down. Experts think the glitch will probably show up throughout the first quarter of next year as software comes into contact with a Year 2000 date.

Clinton warned that "no amount of preparation can prevent us from glitches" and urged smaller businesses and local governments to "make every effort possible to fix as many computer systems as they can."

He thanked "the thousands of dedicated men and women of the federal government, who spent long hours, late nights and many weekends, getting us ready for the New Year."