Budgets come in so many disguises, it's hard to find the real McCoy among the imposters. But when House and Senate conferees resume work this week on the budget, the real McCoy will be on the table.

Our budget plan is a product of solid political bloodlines, supported by three Republicans and three Democrats, a majority of the Senate conferees.

The plan gets the job done with hammer and nails, not smoke and mirrors. By Fiscal 1988, if it is passed, the deficit will be down to $71.9 billion. By Fiscal 1990, the deficit will be gone. We won't have to come back next year for further "adjustments," and there won't be any more "downpayments." This plan hits the deficit in each of its four pressure points.

First, the plan cuts federal spending. Revenue sharing ends after 1986. Medicare savings total more than $18 billion in three years with no extra burden to beneficiaries. Agriculture cuts reach $12 billion by 1988. Domestic savings total $117 billion over three years.

Second, military spending is frozen in 1986, then allowed to grow by three percent in both 1987 and 1988. The nation has bought itself a powerhouse defense, and it's on delivery. Under the plan now before the conferees, the nation will still buy $300 billion worth of protection in each of the next three years.

Third, cost of living adjustments (COLAs) for Social Security and other retirement programs are suspended for one year. A 20 percent plowback of savings will safeguard the low-income elderly, and full COLA adjustments will resume in 1987.

Fourth, between 1986 and 1988, the plan calls for $59 billion in new revenues. None of those dollars will be used to fund new spending programs. Instead, they'll all be used to reduce the federal deficit.

Those are the four parts of the plan. It can be passed. And here's what makes it necessary.

Our plan rests on one, blunt assumption: unless we use all the budget tools available, we will have $200 billion deficits indefinitely. Budget Director David Stockman told the New York Stock Exchange exactly that last month. By 1990 the interest on the national debt will nearly equal what we now spend on national defense. Our foreign trade deficit will be running neck and neck with the federal deficit.

From the long list of negatives, select any one -- from high interest rates to lost jobs -- and the conclusion is the same. We either reverse the deficit trend this time, or it will never be reversed. This is the last chance to act while we still have some measure of control. And this is the one chance we have between last year's election and next year's election to deal with economic facts as we find them rather than as we wish they were.

Ever since the budget conference began, it has been marked by political suspicion. When sessions were suspended June 25, it was because neither house would move from the corner into which it had painted itself. Conferees were seen as either anti-defense or against Social Security depending on whether they supported the House or the Senate budget. As long as those remain the only two choices, the suspicion and deadlock will continue.

The budgets separately approved in the House and in the Senate each put two of the three deficit-reduction elements off limits. The house exempted revenues and Social Security. The Senate protected revenues and the military. The only way the deficit can really be eliminated is if all the big-ticket items are part of a fair package. What's needed now is a decisive step to demonstrate that no one's getting the upper hand at the expense of someone else.

The question, of course, is whether the administration will go along with the Senate's budget offer. Precedent suggests the White House could check in at the "last resort" without embarrassment. It's happened before.

Twice, President Reagan has made tax hikes possible when the economic facts made them essential. And both the White House and members of both parties in both Houses are still skittish about asking for more revenues. But when it was clear in the past that everything short of revenues simply wouldn't keep the deficit from climbing, we did what was necessary for the good of the country.

The same situation exists right now. We simply can't cure the deficit with spending cuts alone. We simply can't grow our way out of the problem while annual interest on the national debt chews up the growth and then some. And we won't be able to do anything at all unless the conference deadlock is broken with a bipartisan agreement.

Our budget alternative gives the president nearly everything he asked in spending cuts. It leaves the military buildup intact, while unifying both the public and private sectors in the most serious effort ever made to cut federal deficits.

We represent a majority of Republican and Democratic conferees from the Senate who have been working for a month, trying to negotiate deficit reduction within narrow bounds. It has not worked. We have become convinced that only a dramatic effort that opens all doors and gets the job done completely can move the conference and Congress. It is time for Republicans and Democrats, representatives, senators and the president to face the economic facts and act for the good of the country. The sooner it's done, the better.