Federal prosecutors preparing for next month's retrial of Maryland Gov. Marvin Mandel today subpoenaed the records of Mandel's 1973 divorce proceedings, which had been sealed by the presiding Baltimore city judge. The subpoena was signed today by U.S. District Judge Robert L. Taylor at the end of an open pretrial conference to set up ground rules for Mandel and his five codefendants on charges of political corruption.

Throughout the two-year investigation into the governor's business relationships, which culminted in his undictment in November, 1975, prosecutors never subpoenaed the divorce records. Nor did the subject of the divorce settlement - which has never been fully detailed in public - arise during testimony in the Mandel's aborted 13 week trial.

After revealing the subpoena in open court today, prosecutors refused to comment on why the divorce information might now be relevant.

Only a few independently revealed details about the degree of financial support Mandel must provide to his ex-wife Barbara have ever come out: a $54,000 loan Mandel received from the Pallotine Fathers and a $100,000 life insurance policy partially paid for by Tidewater insurance, Inc., a company owned by several Mandel codefendants.

The governor is charged with accepting loans,vacations, and valuable gifts from his five codefendants in the case - businessmen W. Dale Hess, Ernest N. Cory, Harry and William Rodgers, and Irvin Kovens - in return for manipulating racetrack legislation to benefit the businessmen who secretly owned the Marlboro race track.

And during the last few years, the most obvious period of financial troubles for the governor were the months surrounding his divorce from his first wife, Barbara Mandel.

Between paying for his attorneys and settling with his ex-wife, Mandel said in a 1974 interview, his lifetime savings were reduced from $78,000 to $5,000.

He also reportedly received a $50,000 loan from Kovens, a powerful Baltimore political figure,to defray his legal expenses during the divorce.

Kovens, a codefendant in the Mandel case, did not stand trial with the other defendants last fall because he had had a heart attack a few months before. Last month, however, Judge Taylor rejoined Kovens' case with those of the others.

A mistrial was declared in the first trial Dec. 7, shortly after the prosecution had rested its case, because several jurors had overheard a television news bulletin about two attempts to tamper with the trial.

The retrial of the case is scheduled to start April 13.

Mandel defense attorney M. Albert Figinski said today that he will consult with chief defense counsel Arnold Weiner and the governor before deciding whether to contest the subpoena for the divorce records. "I don't know that we care much" about the prosecutors seeing those records, Figinski said.

By late this afternoon, the subpoenaed divorce files were in the custody of Anselm Sodaro, chief judge of the Baltimore City Supreme Bench. Sodaro's law clerk, John Boyd, said that Sodaro would turn over the records to prosecutors by March 14 if Judge Taylor ordered it.

Attorneys representing Barbara Mandel in the divorce proceedings could not be reached for comment on the subpoena.

During the brisk three-hour hearing that proceeded the issuance of the subpoena, Judge Taylor, who is the third judge in the past year to preside over the Mandel case, made it clear that he intends to move the trial along as fast as possible - particularly since he intends to sequester the jury. Taylor even mentioned finishing the trial in six weeks, but Assistant U.S. Attorney Barnet D. Skolnik, pointed out that it had taken eight weeks last fall to present only the government's portion of the case.

Judge Taylor then amended his estimate of the trial's length to eigth to 10 weeks. The trial will run six days a week until a jury is picked, he said, then five days a week from 9 o'clock in the morning to 4 o'clock in the afternoon.

Two defense attorneys in the case, Thomas Green and Charles Bernstein, complained mildly after the judge asserted that he would sequester the jury in the case.

Bernstein, the public defender hired to represent Cory since he was declared an indigent at the close of the first trial, complained that, by deciding sequester the panel, "We'd be ruling out the kind of people that would grasp the complexities of this case."

Today's pretrial conference in open court is unusual for Maryland according to observers. However, when he first took over the case in January, Judge Taylor told the attorneys rather testify that he intended to have as little of the trial as possible conducted in secret.

The 13-week trial last fall was frequently interrupted by lengthy whispered conferences at the judge's bench and even lengthier sessions in the judge's chambers.