IT'S PROBABLY NOT marked on your calendar, but for those of us who follow politics, this is an important anniversary. It was 10 years ago today--on April 7, 1972--that the Federal Election Campaign Act went into effect, and presidential candidates could no longer accept anonymous and unreported contributions.

In recent months we have seen the president's budget director assail lobbyists seeking tax breaks as "pigs at the trough" and have heard stirring denunciations of the political action committees that contribute to the campaigns of congressmen who support their industry's or company's favorite bills. There are doubtless abuses of the political process here. But they are as nothing to what was happening at 1701 Pennsylvania Ave., at the office of the Finance Committee for the Reelection of the President, up to the midnight deadline 10 years ago.

Right up to that April 7 deadline, Maurice ("Give me back my good name") Stans was almost literally shoveling in hundreds of thousands of dollars of cash contributions--none of which had to be reported, and few of which ever were. There were no literal bushel baskets or wheelbarrows full of money, but the atmosphere, to judge from the testimony later before the Senate Watergate committee, was much the same as if there had been.

In fact, so generous were various contributors that not all the money could be counted or even collected by April 7. Hugh Sloan, the finance committee's treasurer, said that Stans himself had lost control of a "runaway situation," and the committee later counted as a pre-April 7 (and therefore unreported) contribution money that had been pledged, or promised, or whatever, but not actually handed over until after the April 7 deadline.

Mr. Stans, who has been nominated by the Reagan administration to be a member of the board of the Overseas Private Investment Corporation, later claimed that his pre-April 7 contributors had a right of privacy--that they were shy people who didn't want to be solicited for other contributions, perhaps, or rich idealists afraid of becoming targets for kidnappers. But in the Washington of 10 years ago, there was the smell of government up for sale, and there were plenty of allegations later that favorable government decisions--for the dairy lobby, for Robert Vesco, for ITT--were rendered in return for pre-April 7 contributions. Executives of big corporations were solicited, apparently systematically, for anonymous contributions on the order of $50,000 or $100,000 to the incumbent president.

Altogether, the Finance Committee for the Re- election of the President took in more that $20 million before April 7, 1972--some $1,700,000 of it in cash. What the contributors received, besides the satisfaction of giving, we will never know for sure. April 7, even if it isn't marked in special ink on your calendar, is a good day to remember every time you get nostalgic for the politics of the good old days, before the campaign finance laws went into effect. There were days when the gang at the trough fed more greedily, and with infinitely greater privacy, than they can today.