Proposals attributed to the Reagan Pentagon transition team for some $20 billion in additional defense spending this year follow indications that a $30 billion to $50 billion cut in domestic programs is in the offing.

Whatever the justification in either case, it will be difficult to achieve such goals if the sacred cows of the Defense establishment are to remain at the feed bin.

In 1972, an Army War College study of the National Guard and Reserve forced identified and verified potential savings of $100 million per year in funds being spent to "train" people whose civilian skills are almost immediately transferable to military uses. For example, lawyers, "civil affairs" specialists, state headquarters clerks and truck drivers are authorized as much paid training time as riflemen and tank battalion commanders.

The Department of Defense adopted the Army suggestions and made several attempts to get them though Congress. Each failed because of opposition from the Reserve Officers Association and the National Guard Association. (Yet the list of units in which savings could be made had been verified, and often expanded, by National Guard and Reserve generals.)

In today's dollars, the potential drill-pay savings along total about $500 million, a substantial part of the additional money the Reagan transition team says it needs.

The same Army War College study found that probably an even larger amount is being spent each year to train thousands of officers who will not be permitted to make a full contribution because National Guard and Reserve units are run as a system of private clubs. The Army Reserve was forced to accept some corrective measures, but no one to date has dated to attempt any effective change in the National Guard.

Meanwhile, the Army continues to be saddled with three separate logistic systems; one for the active Army, one for the National Guard and one for the Army Reserve. At the same time, separate Guard and Reserve administrative structures, with their expensive duplicate galaxies of generals and their headquarters, remain firmly in place despite a dramatic decline in strength in both components during the past decade.

The Department of Defense tried and almost succeeded in 1964-65 to create a more rational and economical Guard and Reserve structure. The attempt failed because the planners did not understand the need to take the National Guard state headquarters out of politics.

The basic concept, however, by which the overall structure would be managed at the state level conforms to the Constitution and to experience, provided the president disabilities in regard to efficient officer utilization are overcome.

If the Reagan team is willing to grasp that nettle, it would be a simple matter to move on to the large-scale waste of productive time, recorded on Pentagon bulletin boards every day, by which entire office staffs are assembled to eat cake and watch someone have a medal pinned, he handed a certificate of something or other or simply be bid adieu.

And all that, I suspect, is only the tip of an iceberg.