When a trusted aide of Ronald Reagan promptly informed him just before 6 p.m. last Wednesday that the price for General Ford on the ticket was Henry Kissinger as secretary of state and Alan Greenspan as secretary of the Treasury, a startled Reagan blurted out: "You're kidding!"

This inflationary asking price by Ford predetermined Reagan's decision hours later. What was planned by the former president and his agents was a restoration of the Ford Presidency, totally unacceptable to Reagan. The fact that Reagan vetoed the unseemly business 90 minutes before Ford's famous interview with Walter Cronkite was supposed to have killed it puts a new light on the Republican presidential nomine. Reagan is decidely less guilty of dishonoring the presidency and more aware of the grave trust he covets. For that reason, it is worth recounting fresh details of Wednesday night based on firsthand observations by several Reagan insiders.

After Ford opened the vice presidential door wide in his Cronkite interview, Reagan told advisers in his 69th floor suite: there is no way that I could take Ford under these circumstances; in the eyes of the world it would look like a deal; we cannot accept.

Why, then, did the Republican presidential nominee allow the matter to proceed, to his own and his party's ill repute?

The answer goes to a question not fully understood by any politicians outside the inner Reagan circle. Reagan and his forces, on the verge of complete party control, felt besieged by Republican heavyweights generously financed by the Republican National Committee. Rightly or wrongly, Reagan felt he would be blown out of the water if he pushed the off buttom.

"The governor knew at 6 o'clock it was no go," one aide told us, "but he also knew there was to much momentum to stop it cold. It had to cool for a few hours."

Shortly after 6 o'clock, Reagan political director William Timmons entered the candidate' s suite. His feet propped on a chair watching the television networks steadily closing in on him, Reagan said: "Maybe this ticket never was meant to be." Upstairs, negotiations were grinding away. Reagan's own veto was a secret inside the Reagan suite.

A Reagan agent, planning what he knew would have to happen later, called an adviser of George Bush for the answer to this question: does Bush support the entire Republican platform? The question, never asked before, was quickly answered: yes, Bush did (Ford did not).

Meanwhile, Reagan ruled out Kissinger and Greenspan for the Cabinet. He felt that Kissinger as secretary of state would at once take over about 50 percent of his administration. Reagan called Greenspan "a good man" but agreed that at the Treasury he would control another 25 percent of the new administration.

Ford men modified the scenario. At 9 p.m., Reagan telephoned Ford and informed by him that Kissinger was taking himself out of the action. By 10:40, Ford's terms were these: Kissinger's role downgraded to "foreign affairs adviser" to President Reagan; Ford to control appointments to the powerful Office of Management and Budget and the National Security Council.

There was more. Ford would have veto power over two Cabinet appointments: State and Defense. Reagan aides William J. Casey and Edwin Meese brought that word to Reagan shortly after 10:30. Those were the new proposals from Greenspan and ex-congressman John Marsh, an increasingly active player in the Ford camp.

In Reagan's suite, the three networks were carefully monitored. Sen. Robert Dole appeared on the screen saying that he felt sure Reagan and Ford would work something out. Reagan, watching, shook his head at the TV set: "No, Bob," he murmured

When ABC's Sam Donaldson aired a report that Reagan and Ford were about to leave the Detroit Plaza for convention hall, Reagan's aides felt the networks had become an unwitting instrument of Ford propaganda. "We felt quite literally surrounded," one aide told us. From the Reagan side, no word had been put out.

A Ford plan, attributed to Kissinger, surface: ajourn the convention, by now jubilant with Reagan-Ford talk, and continue negotiations until Thursday. Reagan instantly vetoed it: that would only give more space and time for consolidating the Ford takeover.

Ford arrived in Reagan's suite, as the world knows, at 11:30. After he left, Reagan quoted him: "It's my instinct," he told Reagan, "that this thing won't work." Reagan had long since come to that conclusion. He had been far more sensitive to protecting the presidency than the outside world could know.