The two fading stars of the Republican Party gave conflicting descriptions this weekend of how to save the GOP, and in the process demonstrated the deep divisions that persist within their opposition party.

Speaking at a conference of Republican state legislative leaders, former President Ford said the United States is "a moderate nation of moderate people to whom ideology is far less important than practicality."

A hundred miles to the north, in Santa Barbara, Ronald Reagan was saying that GOP must remain a conservative party and warning that conservatives will go elsewhere if it does not. Reagan said he had made this point Thursday at a private meeting with Republican National Chairman Bill Brock.

"I told Chairman Brock that we are Republicans, that we want to work for our principles and our beliefs within the Republican party," Reagan said. "I told him also that we hope that those who are in control of the national party apparatus will never force us to look elsewhere or for other means to advance the cause of conservatism in America."

Ideological differences are not the party's only problem, as an incident involving Brock demonstrated. Ever since Jimmy Carter was elected with overwhelming black support, Republican leaders have been saying that the GOP must attract blacks if it expects to win elections in the future. Brock made this point Thursday at a Republican fund-raising dinner here - and then a chorus sang "Dixie' in his honor.

The insensitivity that Republicans sometimes have shown toward blacks was acknowledged candidly by State Rep. Paul Priolo, the minority leader of the California Assembly and organizer of the conference of state GOP legislative leaders from around the nation. Priolo said he organized the meeting because he doesn't believe that the national party speaks adequately for GOP legislators.

"We don't understand show they think," Priolo said of blacks, "I don't know how to talk to them. We've never made any effort to talk to them. We need to change that."

The result of the Republican failure to represent black people over a long period of time, State Treasurer Jesse Unruh - a Democrat - told the legisltors, is that the GOP now lacks any base in the black community.

THe outspoken Unruh, who was defeated by Reagan for the California governorship in 1970, was invited to the conference by Priolo in an effort to encourage a realistic discussion of GOP problems.

Unruh urged the GOP to "find new allies." He said that Republicans had an ooportunity to attract support among trade unionists and also among Hispanic voters, whom he said neither party represents very well.

Unruh said the labor movement was "very vulnerable to GOP overtures," particularly on issues involving jobs versus environment. To make good on this opportunity, Unruh said, the GOP must overcome a belief among trade unionlists that is a conflict between management and labor the Republicans always side with management.

The state treasurer also said Republicans should try to move in on Democratic issues the way California Democratic Gov. Edmund G. (Jerry) Brown has preempted the GOP issue of fiscal conservatism.

Unruh's advice was remarkably similar to what the Republicans heard the day before from Detroit pollster Robert Teeter, who did the survey research for Ford's 1976 election campaign.

Teeter presented survey results that depicted the voter as basically unideological. Often, Teeter said, a voter who described himself as "conservative" was refering to his life style, not his politics.

The survey showed that the chief concerns of Americans were owning a home and having a good job. These were followed, in order, by health care, educational opportunities for children, and recreation availability. Teeter said few Republican candidates displayed sharp identification with these concerns.

The pollster though the GOP should attempt to attract the increasingly large number of voters who do not participate in elections. Many of these are young working people who have never voted because of what Teeter called ta sense of cynicism and alienation" about politics.

Teeter, Unruh and Ford gave similar advice on the need for the Republican Party to accommodate various ideologies within its ranks.

"If there are people in the party you don't like, my advice is that you wait until you get back into a strong majority position before you kick hell out of them," Unruh said.

Unruh's example of a Republican politican who behaved pragmatically in office was Reagan, who as governor was "not the hardnosed conservative he portrayed himself to be."

But Reagan played the conservative role this weekend, in his speech to the California Republican Assembly in Santa Barbara and in his meeting with Brock. Reagan has been described by associates as increasingly concerned with what he sees as Brock's reluctance to criticize President Carter.

Reagan occupies an independent position now as head of Citizens for the Republic, a political action committee funded by $800,000 left over from the Reagan presidential campaign.

Increasingly, both Reagan and Ford are talking as if they expect to be presidential candidates again. This disturbs some Republican officeholders in California, who see a continuing Ford-Reagan conflict as damaging to party chances in the state in 1978.

That this division is likely to continue seems assured after Ford's speech here Saturday, which was regarded by Republican officials as an open challenge to Reagan.

"A contest within our ranks to prove who is the purer of ideology will not attract the American people," Ford said. ". . . They prefer common sense to conservatism and/or liberalism, and if we are to earn the support of the American people we must prove ourselves to be the party of common sense and results."