Republican Rep. Stanford E. Parris and former Democratic Rep. Herbert E. Harris II have agreed on one thing during their raucous campaign for Congress in Northern Virginia: The issues are, as Parris said, "the economy, the economy and the economy."

Parris has focused his speeches and ads on "the tax and tax and spend and spend policies" that he says Harris pursued before Parris knocked him out of Congress two years ago.

With unemployment holding at about 4 percent in the wealthy, well-educated suburban 8th District, Harris has chosen not to wage this year's classic Democratic campaign against the recession, unemployment and bloated military spending. Instead, he has concentrated on warning those dependent on the federal government -- the federal workers, federal retirees and Social Security recipients -- that Parris and his Republican colleagues have gravely endangered their economic security.

Most polls support the candidates' belief that the election, the third Harris-Parris match in a swing district that both national parties view as winnable, will be decided on the basis of personality, get-out-the-vote efforts--and economics. Despite their single-issue strategies, however, the candidates, along with Citizens Party nominee Austin W. Morrill Jr., have aired differences on other issues during more than a dozen appearances in the district, which stretches from Alexandria south through Fairfax, Prince William and Stafford counties.

* Harris supports the Equal Rights Amendment and says he would reintroduce it in the House and lobby vigorously for its approval. Parris at first declined to take a position on the amendment, and two years ago said he did not support it, according to a taped debate Harris aides have gleefully replayed. Recently Parris said he would support an ERA measure identical to the one that died unratified this year.

* Parris said he supports a constitutional amendment allowing voluntary prayer in schools. "The Congress does it every morning, and I don't see any reason the people who go to our public schools should not have the same opportunity," he says. Harris opposes it. "Let's not place any child in our school system in the position of feeling he or she is being pushed into a corner because of his or her religious beliefs," Harris says.

* Parris said he supports some changes in the Clean Air Act, "minor modifications to ease regulatory burdens." Harris said he favors extending the act in its present form. "Anybody who says it is good business to lower air quality standards doesn't understand the costs of hospitalization," Harris told an unreceptive Fairfax Chamber of Commerce.

* Harris said he favors outlawing "Saturday night special" handguns, though he opposes control of sporting guns. Parris opposes gun control, saying it would be unenforceable even if it were desirable.

* Parris has pressured federal housing officials to kill public housing projects in several Fairfax neighborhoods, and he told one audience he would "defend your right to have a say on whether a low-income project will be located in your district." Harris sidestepped a question on the subject, saying, "I got into civic work to protect communities and work against those developers who would impact on us adversely."

* Both men tout their success in local matters, Parris pointing to his efforts to resolve Alexandria's dispute with the federal government over who owns the city's Potomac riverfront and Harris to his success in obtaining funding for Metro during his six years in Congress.

Neither candidate, however, has spent much time talking about local issues, and they have revealed few differences on foreign or military policy. Both, unlike Morrill, oppose a bilateral freeze on nuclear weapon production.

Instead, Parris at every possible opportunity blames the recession on Harris, Jimmy Carter and House Speaker Tip O'Neill. Harris just as frequently warns pensioners and federal workers, who he said will cast half the votes in the district Nov. 2, that the Republicans will harm them if they have a chance.