In his only on-the-record appearance this week, Secretary of Defense Robert S. McNamara suggested Monday that a national lottery "would be one of the means of eliminating the deficiencies" of the present Selective Service system.

He pointedly avoided any commitment to the proposal, insisting that he would save his specific recommendations until December, when the President's Commission on the Draft will release its report. "It would be tactless of me to comment before they report," he explained.

But, in answer to a question about the feasibility of the lottery, he said that such a system would perhaps end both the uncertainty and inequity of present draft methods.

During the interview, conducted jointly by the Crimson and WHRB, the Secretary also:

A tape of this interview with Secretary McNamara will be broadcast at 7 p.m. Thursday on WHRB (550 AM, 95.3 FM).

* urged that the Army be charged with rehabilitating more of the men who are now rejected on mental and physical grounds.

* chided college students for the "lack of a feeling of obligation" to perform service for their country.

* criticized the country's failure to provide sufficient funds to meet needs in education, health, and conservation, and recommended "tax increases at state and local levels" to provide the revenue.

In reforming the draft, McNamara recommended "work on two fronts simultaneously: one, building the feeling of obligation, and two, making it much easier for individuals to find opportunities that fit their skills or interest" whether in the military or alternative service.

Current draft methods are clearly unsuitable, he said, because they have led to uncertainties and inequities -- uncertainties because "we draft the oldest first. It's never clear exactly at what age one will be subject to the draft and this makes very difficult the planning of one's personal life."

As evidence of the inequity, McNamara pointed out that only 30 perment of young men with less than an eighth grade education and roughly 25 percent of those going on to graduate school ultimately serve. But about 70 percent of the men who attain some level of education between these two groups see military service.

A lottery, McNamara said, would require that every young man take his chance with the draft at some time, most likely at age 19. "Every 19-year-old would be subjected to it," he explained, but deferments could continue for educational and other reasons. Thus, after drawing at 19, every man would know precisely where he stood.

Any deferment, however, would carry with it an obligation for the man to throw his name back into the pool at the end of the deferred period -- thus eliminating the inequity associated with the present 2-S deferment.

Any proposal for reform must be based on what the Pentagon has gradually learned about its manpower supply, McNamara insisted. He divided the 1.8 million men who reach eligibility for service each year into three parts.

"One-third are required normally for the military," he said. "An additional third are capable of serving, but not required, and the remaining third have been thought, in the past, incapable of serving for either medical or physical reasons."