The highest government official convicted in the Ill Wind investigation into Pentagon procurement fraud was sentenced to 15 months in prison yesterday for conspiring to illegally help a Connecticut-based defense contractor compete for a $100 million Marine Corps communications contract.

George G. Stone, a procurement director with the Space and Naval Warfare Systems Command, pleaded guilty in May to conspiracy and conversion of government property.

The fifth government official brought down by Ill Wind, Stone admitted that he funneled confidential information about the communications contract to a friend who made sure that it reached executives at Norden Systems Inc. in Connecticut.

Stone, 46, also conceded in court papers that he intervened to reinstate Norden when the company was eliminated during the middle stages of the competition. Norden withdrew its bid on the Marine Corps project when the Ill Wind investigation surfaced in June 1988.

Stone's sentencing broke a sustained lull in the Ill Wind investigation, which passed the two-year mark last month.

Defense attorneys and some government officials have criticized the investigation, which has resulted in convictions of four corporations and 34 individuals, most mid-level marketing employees and independent defense consultants.

No trials are pending; two defendants are awaiting sentencing. One, defense consultant William M. Galvin, pleaded guilty in March to conspiracy and bribery for allegedly paying Melvyn R. Paisley, a former assistant secretary of the Navy, to illegally award an Israeli firm a $100 million contract for drones used in battlefield reconnaissance.

Robert Plotkin, Paisley's attorney, has denied that his client was involved in any bribery schemes. Paisley has never been charged in the case.

Brian P. Gettings, Stone's attorney, argued yesterday that Stone "was kind of a victim in this case." Gettings said Stone's role was limited to providing information to Mark C. Saunders, Stone's former boss and a close friend who left the government to form an independent consulting firm.

Saunders, the second Ill Wind defendant awaiting sentencing, and three former Norden executives have been convicted for their roles in the scheme.

Gettings also noted that Stone never sought or received any payment for the inside information. "He stood to gain nothing, and in fact he gained nothing," Gettings told the court.

But U.S. District Judge Claude M. Hilton said before passing sentence that Stone sealed his fate when he chose to disclose confidential information on how Norden was faring in the competition.