One of the big three postal unions has split ranks and tentatively agreed to a separate three-year labor contract covering the 50,000 members of the mail handlers craft, most of whom load mail on trucks. The mail then is sorted by clerks, and delivered by letter carriers represented by other -- and often rival -- unions.

Mail Handlers Union President Glenn Berrien called it a compromise that protects members' jobs and cost-of-living adjustments, while guaranteeing that members will continue to pay much less for health insurance than non-postal federal workers. Members would get a $900 lump-sum bonus this year and next year and $600 in the final year of the contract instead of a regular pay raise.

Moe Biller of the American Postal Workers Union and Vincent Sombrotto of the National Association of Letter Carriers angrily denounced the action of their AFL-CIO affiliate, calling it a "disgraceful contract" that could "undercut" nearly 500,000 clerks and letter carriers during the contract arbitration process that begins next month with the Postal Service.

Arbitration was set in motion in November, when the unions and the Postal Service failed to agree on a new contract. The current three-year agreement expires this year.

Berrien, whose union has had a long-running turf war with the APWU, said the agreement recognizes that the Postal Service must cut $1 billion during the next five years; the service already has threatened to reduce its 800,000-employee work force by 145,000.

"We saved the cost-of-living adjustments, which the Postal Service wanted to eliminate," Berrien said. "Sure, a pay raise would have been better, because {they count toward} other benefits and base pay."

Berrien said that continuing the adjustments is essential, and that they have been worth more in members' pockets during the past three years. During the current contract, workers got about $1,800 in guaranteed raises, but more than $2,500 in COLAs.

Berrien said the Postal Service dropped demands that workers pay more for their insurance, and the union agreed that future mail-handler hires will earn 20 percent less for their first 96 weeks of service, before going to the regular pay scale of $22,000 to $27,000 per year.

APWU and NALC will urge mail handlers to reject the contract. Biller, whose union represents about 3,000 of the 50,000 mail handlers, said the tentative agreement is "a joke . . . it stinks."

The APWU-NALC contract will be decided by arbitration, which will begin next month and will take about 45 days of hearings and arguments. Sorry, Wrong Number

Yesterday's item about the voluntary contributions program listed the wrong number for the Federal Employees Almanac, one of the best sources of information about the plan. To order the almanac call 703-533-3031.

The voluntary plan allows eligible employees to contribute up to 10 percent of lifetime base pay -- by check -- in multiples of $25. Anyone interested must fill out a Standard Form 2804, "Application to Make Voluntary Contributions," available from personnel, or the Office of Personnel Management's Retirement-Insurance Programs Office, Washington, D.C. 20415.