Edward J. Gurney, private citizen, still sends letters out on his U.S. Senate stationery. His aides call him "senator," and his roadside signs say, "Re-elect Ed Gurney to Congress."

Gurney, however, isn't in Congress. He hasn't been since 1974 when he was indicted on seven counts of bribery, conspiracy and perjury.

But the handsome, silver-haired war hero who rose to prominence as Richard M. Nixon's staunchest defender on the Senate Watergate committee desperately wants to get back in.

"He wants to go back to Washington," says his campaign spokesman, Ed Nellor. "It's what he knows how to do best. He enjoyed the hell out of it up there."

The fact of the matter is that Gurney, once the golden boy of Florida politics, never reestablished a private career for himself after he left the Senate four years ago "to fight to clear my good name."

His life has been surrounded by personal tragedy. Although he was acquitted of charges, two long trials left him bitter and financially strapped. His wife, an invalid for eight years, died. The prospect of going back into law practice bored him.

Gurney refuses to meet with out-of-town reporters to talk about his reasons for running, and he has avoided joint appearances with his little-known opponents in tomorrow's primary.

"He doesn't ever use the words that he wants to vindicate himself. He's vindicated in his own mind," says Nellor. "But obviously a guy who has gone through what he has must say to himself in his darkest days, 'I'm going to show them.'"

His comeback campaign should be a political classic. For Gurney, the old pro who has been through the wringer, is in for what may be the toughest election of his life in November against upstart Democratic state Rep. C. William Nelson, who portrays himself as a "fresh face with a clean record."

The race is for the House seat now held by republican Lou Frey, Gurney's former law partner who is running for governor. Gurney represented the district, which includes Orlando and Cape Canaveral, before he was elected to the Senate in 1968.

For pure drama, central casting couldn't have come up with a better opponent. Nelson is young, rich and articulate. He has a Yale education, an attractive wife, two cherubic looking children and all the earnestness of an Eagle Scout.

On the stump, he talks about financial disclosure, oponness is government, and the "time for a new generation of leadership." He seldom mentions Gurney by name, but the implication is always there that the former senator is part of a shady crowd that practices "politics of business as usual."

Gurney, meanwhile is running as a congressman emeritus, an elder statesman, who has been around the track and knows all the players.

"It's principally a race between a man with experience and know-how, one that knows Washington, an ex-Republican leader with an excellent reputation, and a young man with youth on his side, but no experience in national politics," he told one reporter.

The contest is shaping up into one of the most expensive congressional elections in Florida history. Although neither candidate has serious primary opposition, Nelson has already raised $144,000; Gurney, $101,000, including $8,000 from the Republican National COngressional Campaign Committee.

Republicans have held the seat since it was created in 1962 winning it every two years by comfortable margins. But registered Democrats outnumber Republicans by a 60-40 ratio in the district.

Nelson, 35, believes it will swing Democratic this year.Fearing Gurney will try to label him a liberal in the conservative district, he has staked out conservative positions on government spending, foreign affairs and defense spending. His campaign literature boasts about his service on a state appropriations subcommittee that cut $42 million from the Florida budget.

Gurney, 64, has 90 percent name recognition in the district, and has never lost an election. For years, he was an unstoppable political force here, moving from the city commission in this Orlando suburb, to mayor, to congressman, to the U.S. Senate. He was the first Republican ever elected to the Senate from Florida, the first candidate in the state ever to win a million-vote mandate.

Today he lives alone in a big house on Lake Osceola that is up for sale. He shops for his own groceries, mows his own yard, types his own letters.

"You wonder [why] I'm bitter?" he asked a reporter from the Orlando Sentinel Star last year. "They destroyed my career."

Nelson realizes that Gurney's comeback bid has a certain appeal. "The man has had a very tragic life," he says. "His wife died. His son committed suicide. There'll undoubtedly be some sympathy votes for him."

Some Republicans are less than enthusiastic about Gurney. For some, he's a reminder of Nixon and what he did to the party. For others, he's simply over the hill, a man passed by events and circumstance.

Dottie Plater is one of them. She is one of Gurney's neighbors, and worked as a "Gurney girl" in his earlier campaigns for the House and Senate. She belives "he got the shaft" in being indicted.

But this year she is working for Nelson. She met him when he knocked at her door a couple of weeks ago.

"It's so great to have a candidate who can read you, who knows what you are thinking," she said at a Nelson coffee the other day. "Originally, I hoped that Gurney would run. But now I think he's beyond his prime. I'm ready to go with a new man."

The crowd of several hundred women at the coffee held in one of Gurney's strongholds here impressed her. "I'm very surprised to see so many women here that I know who had Gurney inclinations and have always been Republicans," she said. CAPTION: Picture, Edward J. Gurney: "You wonder [why] I'm bitter? They destroyed my career."