Ronald Reagan and George Bush premiered their new unity roadshow today, with the presidential nominee calling his campaign a crusade for which the Republican Party is ready "as never before."

The show, scheduled to tour the nation for the next four months, went off without a hitch -- or an ounce of drama -- as Reagan and Bush appeared at a series of postconvention meetings with party leaders.

Bush, Reagan's most persistent challenger for the GOP nomination, made it clear that he is prepared to be a subservient running mate.

He walked a few paces behind Reagan. He said on a morning television talk show that he had not bothered to ask what his role as vice president would be. And he appeared to made a 180-degree turn on a host of issues he had championed in winning the hearts of party moderates.

"Those who want to seek some little difference or remind someone of something out of the past. I'm not going to be part of that at any time," Bush told the Republican National Committee, which met four blocks from Joe Louis Arena, where workers were rapidly dismantling the facilities built for the convention.

It was a theme Bush has struck repeatedly since becoming Reagan's No. 2 choice for the No. 2 spot after negotiations to get former president Gerald R. Ford on the ticket fell through.

Bush has sounded defensive, afraid to say anything that would hint at any disagreement with Reagan, whom he sometimes bitterly attacked during the primaries.

"Yes, I know people will be saving, 'He said this and he said that,'" Bush told party leaders. "But I'll be trying, and succeeding, because I'm simply not going to dwell on the differences. I'm going to say, 'Look, President Carter is the issue and the Democratic Congress is the issue.' That's the way we're gong to handle that."

Meanwhile, an estimated 22,000 bleary-eyed GOP foot soldiers and the reporters who noted their every twitch folded their toy elephants and packed their outlandish hats, cameras and skyboots in preparation for going home.The prices of elephant buttons and T shirts fell as fast as the hotel rooms emptied.

Detroit was left to count the take -- $40 million by preliminary estimates -- that the conventioneers pumped into the staggering local economy.

There was a bit of staggering along the shores of the Detroit River Thursday night after the gavel rapped for the final time and the last balloon was popped, and everyone adjourned to p arty suites and bars.

By this morning, many of them -- dazed at the culmination of months of caucausing, committeeing, campaigning, consensus-building and coming together -- found comfort in shared misery.

At a Republican National Committee meeting, Chairman Bill Brock made about four successive flubs -- wrong names, wrong titles -- and, sighing, said to a colleague: "I think I've caught your flu. When I first got up, I thought it was polio."

Reagan told the committee that the convention had been a "dream come true" in terms of unifying the party and ending the internal squabbles.

He said he was "confident millions of Democrats and millions of independents" will rally behind his banner because "they are as miserable and unhappy as we are with conditions in this country."

"It is a crusade and this time we're ready for it -- all of us," he said.

Reagan told a later meeting that "we have a fighting chance" to capture both houses of Congress. Democrats have "had the whole enchilada since 1976," he said. "they can't point the finger of blame at anyone else."

Early in Thursday night's convention session came a brief moment that helped mark the putting aside of the fierce grudges between the wings of the party.

At the urging of New York's liberal Sen. Jacob K. Javits, the thousands of conservatives on the floor, who had so long railed against what they called the eastern establishment, bowed their heads for a moment of silence in memory of Nelson A. Rockefeller, who had been their arch villian for many years.

Reagan forces picked up the same theme at today's committee meeting, extending until January the term of Brock, whom conservative forces had attempted to oust last month.

"The Republican Party is alive and healthy, and our present chairman deserves a large share of the credit for this condition," said Drew Lewis, the new deputy chairman and Reagan's hand-picked representative at GOP headquarters.

But the party did pick a replacement for Mary Crisp, its controversial former cochairman, who had protested the platform's abandonment of support for the Equal Rights Admendment and created a stir in Washington when she had her office checked for electronic bugs.

She was replaced by Betty Heitman, president of the National Federation of Republican Women, who has refused to take a position on the ERA.

Reagan and Bush are to leave Detroit Saturday for Houston, Bush's home, where they will appear at a rally. Reagan then is to continue to California, and plans to spend several days at his ranch near Santa Barbara. cBush is to go to his vacation home in Kennebunkport, maine.

After spending most of the last five days in his 69th-floor hotel suite here, Reagan told audiences today he was tired of "living in one of these places where they won't let you open the windows. I can't stand the artificial air."