IN 1886 Henry Grady, proprietor of the Atlanta Constitution, proclaimed the emergence of a "New South." It was the first of a long string of similar proclamations, many of them deserved. The latest proclaimer of a New South is Bert Lance, who was President Carter's first budget director and is now chairman of Georgia's Democratic Party.

Georgia seems likely to have one of the nation's earliest presidential primaries next year, so Mr. Lance has been addressing his current thoughts to candidates for the 1984 Democratic presidential nomination. His message to them is that you can't win without the South, and to win the South you must be a "mainstream" candidate who wears "conservative" stripes. You should be more interested in getting a southern vice presidential running mate (if you're not southern yourself), Mr. Lance advises, than in propitiating Yankee interest groups like labor, blacks, feminists and gays.

All well and good: the candidates are grown-ups, and they can evaluate advice from Mr. Lance or anyone else. But we think it's worth noting exactly in what ways the South that he is touting is new. Consider civil rights. The South now accepts national civil rights laws as much as the North does: most southerners in Congress supported extension of the Voting Rights Act. There is no need anymore for a Democrat (or Republican) to be especially "conservative" on civil rights to propitiate the South. Similarly, on many economic issues, liberal Democrats are no longer talking about income redistribution schemes. The programs they do support--food stamps, school lunches, aid to education --have widespread support in the South as well as the North. The blue-collar vote in the South in national elections is more heavily Democratic now than in the North.

Where the South seems to differ is on non-economic issues on which tone is often as important as content. The tone of debate on foreign policy, for instance remains unabashedly patriotic in the South; people in the North seem more ready to find fault with American policy. Southern voters are also more likely than northerners to believe in traditional religions and moral codes.

Catholics became unconcerned about the presence of a Catholic on the ticket after the election of the first Catholic president in 1960. Southerners, to judge from the votes given the Carter-Mondale ticket in 1980, haven't cared much about the presence of a southerner since the first Carter victory in 1976. The initial soundings of current presidential candidates suggest that few southern voters feel a need to have a southerner on the national ticket in 1984. Voters in today's New South are different, all right, but not exactly in the ways Mr. Lance suggests.