There is an intriguing pattern to the piecemeal reconstruction of the Reagan administration. With each additional change, the current government comes to look more and more like Nixon-Ford days reincarnated.

From George Shultz to William Ruckelshaus, almost every replacement Ronald Reagan has made for a vacated major policy post has been someone who earned his reputation in the earlier Republican administrations.

Such continuity is, in a sense, unsurprising. Jimmy Carter, the previous "outsider" president, reached back for such familiar Democratic Establishment figures as Joseph A. Califano and Edmund S. Muskie to help him govern.

But Reagan came to power as one who had campaigned against the "Washington buddy system" that he said characterized the GOP governments of the 1970s. Many of his enthusiasts believed he would transform the Repub- lican Party on his way to transforming the country, by installing men and women who, like himself, were unencumbered by links to those clubby Republican administrations of the past.

It hasn't quite worked out that way. Consider the major changes that have been made. As secretary of state, the first choice was Alexander M. Haig, whose close ties to Richard Nixon and Henry A. Kissinger were mitigated (in the eyes of true Reaganites) by his outspoken anti-communism and his military background. Now we have Shultz, the ultimate team player, who filled almost as many top jobs in the Nixon- Ford years as Elliot Richardson. He is a Republican Establishment man--and, worse, has been known to consort with Democrats and labor leaders.

The first choice for secretary of health and human services was former senator Richard Schweiker of Pennsylvania, who burned his bridges to the Eastern Establishment in 1976 to become Reagan's designated choice for vice president. To replace him, we have Margaret Heckler of Massachusetts, an Establishment favorite who tied with two other House Republicans in voting most often against Reagan's positions in 1982.

As secretary of transportation, the first choice was Drew Lewis, who abandoned his ties to the Ford wing of the party to organize Pennsylvania for Reagan in 1980, when that was hardly the popular thing to do. To replace him, we have Elizabeth Hanford Dole, who was a White House official under Nixon, was appointed to the Federal Trade Commission by him, and whose husband, Sen. Bob Dole of Kansas, was Ford's running mate in 1976 and Reagan's opponent for the 1980 nomination.

Finally, and most recently, we had the resignation as head of the Environmental Protection Agency of Anne M. Burford, an early and enthusiastic Reagan backer from Colorado. As his choice to succeed her, Reagan reached out to Ruckelshaus, the man Nixon picked to set up the EPA, the man who worked with Richardson at the Justice Department and was fired for disobeying Nixon and Haig during the Watergate mess.

In almost every one of these switches, the movement has been eastward and leftward-- not very far left, to be sure, but into the heart of that pragmatic Republican center the early Reaganites so despised.

You can see the same pattern in other changes. When Washington University of St. Louis' Murray Weidenbaum left his post as chairman of the Council of Economic Advisers, he was replaced by Harvard's Martin Feldstein. When the Hoover Institution's Martin Anderson left as domestic policy coordinator on the White House staff, he was succeeded by yet another alumnus of the Nixon-Ford White House, Edwin L. Harper.

In fact, it is hard to think of a case where a departing Reagan policy official has been succeeded by anyone further right on the political spectrum.

I'm not sure what the explanation is for this. Some of my conservative friends see it as evidence of the "conspiracy" by White House chief of staff Jim Baker and "the Bush network" to infiltrate their moderate allies into Reagan's government.

Others, less conspiratorial in outlook, see these simply as unrelated steps to buttress the operations of the Reagan administration and put politically attractive people into place before the reelection campaign.

Still others suspect that it shows Reagan has abandoned any notion of revolutionizing government and is content with anyone who will help him mind the store and avoid scandal until he is ready to retire.

I can't say which--if any--of these theories is right. All I know is that the pattern has been consistent. A few more resignations, a few more explosions, and they will be sending out for Don Rumsfeld, Mel Laird and--who knows?--utility infielder Richardson.