Maryland Gov. Marvin Mandel may be sentenced to jail in his court appearance today, but even if he isn't several former governors say he is in for a shock in exchanging the pampered world of power and perquisites for the real world of private citizenry.

Former West Virginia Gov. William Wallace Barron, who served four years in prison after his term ended, experienced "the big transition from having everyone do what you want them to do" to federal prison "where you have bad dreams at night, only to wake up in a cell and find they don't go away, that they're real."

Even governors who have made the transition to private life without the onus of a criminal conviction go through what former Kentucky Gov. Edward T. (Ned) Breathitt Jr. described as a "withdrawal period . . . There's nothing more useless than a former governor."

One big adjustment, according to several ex-governors, is having to cope with traffic after years of being chauffeured

Linwood Holton, who was governor of Virginia from 1970 to 1974, and left office without taint, joked that when former chief executives of Virginia got together for a Chirstmas party in Richmond "we approved a motion that would restore to us a state trooper to drive our car, figure out how to get wherever we were going, and park it."

Living in a governor's mansion "is not realistic," said breathitt, who now is public affairs director for the Southern Railway System here. "It's difficult to keep a perspective.

"The kids are spoiled. They have a staff to wait on them, no chores, no rooms to keep straight. My wife and I were spoiled too. She had no meals to cook, and there was always someone to carry your luggage . . . It's like chocolate pie. One piece is great, but the whole thing is too much," he said.

Barbara Mandel, who left the mansion in Annapolis when her marriage to the governor dissolved four years ago, said "the biggest relief for me wa snot having the troopers watching you day and night.It's wonderful not living in a fish bowl, where every time you pick up a drink, someone was watching."

"Living in a 53-room. 100-year-old mansion is not normal," Mrs. Mandel went on. "I always kept in mind that the mansion was just loaned to us, and always knew that someday I'd have to leave, although of course I didn't expect to leave the way I did (because of divorce)."

Dale Bumpers found there was "just no comparison between the perks" he enjoyed as governor of Arkansas and whata he has now as a U.S. senator.

"How the myth of congressional perks is perpetuated, I don't know," said Bumpers, who gave up "big automobiles, chauffers, cooks, advance ment" when he came to Washington, where "my only perk is an elevator that we need to get to roll calls on time."

Bumpers like to tell about the day, shortly after he had moved up to the Senate, that he was waiting for a traffic light as a passenger in his aide's Volkswagen when he was spotted by former Ohio Gov. John (Jack) Gilligan.

"Jack yelled, 'You've kind of changed your mode of transportation, haven't you?" Bumpers recalls, to which he called back, "What are you doing, Jack!" and Gillian replied, "Waiting for a bus."

Gilligan later moved back to a chauffer-driven vehicle as administrator of the Agency for International Development, but an aide said he gave up the car this week in an economy move, and now rides the Metro to work.

Bumpers said his wife Betty "had a pretty rough time adjusting, having to do the laundry and all that stuff after having so much help."

Barbara Mandel "didn't have any family to prepare meals for" after she moved back to an apartment in Baltimore, "so that was no problem for me. But the governor's present wife (Jeanne) still will have a small family to care for."

Arch A. Moore, who succeeded Barron as governor of West Virginia, said his wife Shelley "expressed a great desire to get back into her own kitchen" before they moved out of the mansion in Charleston early this year. "But now the ramance of cooking is gone, and she'd like to get the heck out of the kitchen," Moore said.

After Holton stepped down as governor of Virginia he took "a fiscinating observation post" as assitant secretary of State for congressional relations. But while he enjoyed being associated with Secretary of State Henry Kissinger, "I had more staff than I needed. I wasn't very busy, so I spent a lot of time looking out the window.

Holton said "it's a tough transition from being the big fish in your own pond to going into someone else's pond. People are often reluctant to ask you to do things they think aren't important enough, so you often do nohting. It's good to stay busy, and I guess that's why so many people write books."

Until he was rescued from his private law practice by being named to the state Supreme Court, in 1967, former Virginia Gov. Albertis S. Harrison (1982-66) "damned near went crazy sitting in small law office" in his hometown of Lawrenceville, Holton said.

The shame of her husband going to prison has caused the wife of former Oklahoma Gov. David Hall to move out of the state.

"Jo doesn't want anyone to know where she is," said the governor's mother, Dorothy Hall. "She is happier away from here."

Hall, a Democrat who was elected on a law-and-order platform in 1970, was indicted 72 hours after his term expired in January, 1975. He was convicted March 14, 1975, on charges of extortion and bribery, and began serving a three-year prison sentence last Nov. 22.

A lawyer, Hall was disbarred after his conviction. His mother said, "It hasn't been easy, but we've managed to hold on financially." His wife recently sold their home in Oklahoma City. The Halls two older children are students at Oklahoma State University. The youngest is in high schooL.

Hall is serving his time at the federal minimum security prison farm in Safford, Ariz., where he has met and talked with fellow inmate John Ehrichman. Hall is staying in shape by playing tennis and following a running and exercise program outlined by his father, a former track and football coach. "He's down to his old college weight," his mother said proudly.

Hall's father, William A. (Red) Hall has encouraged his son to be philosophical blames on "political enemies." The elder Hall advised his son to think of the time "like being in the service, except you can call home, and during the war, I couldn't." His mother said "David calls us quite often, but he has to call collect."

Former Gov. Barron, who was paroled March 28, 1975, agreed that "adjusting to prison is very much the same as adjusting to the Army. But of course, if a man had a choice, he'd go to the Army.

Barron was indicted in 1968 on charges of accepting kickbacks on state contracts while he was governor of West Virginia from 1961 to 1965. Although his codefedants were found guilty, Barron was acquitted. But he was indicted again in 1971 and convicted of paying a $25,000 bribe to the foreman of the jury that had acquitted him.

One of the inmates Barron met during his four years in federal prisons was ex-Gov. Otto Kerner of Illinois, who was sentenced by U.S. District Court Judge Robert L. Taylor, the same judge who will pronounce sentence on Mandel today.

While in prison at Eglin, Fla., Barron had "an exciting experience that changed my life. It was the same thing that happened to Chuck Colson. I accepted Jesus Christ, turned my life over to him. It is hard to explain, but it was a miraculous thing. I was born again."

Since his release from prison. Barron has lived in Florida with his wife Opal and he has become active in a local Presbyterian church. He views his selection as a church elder as "quite a comeback, proof that people have accepted me."

He also has been in touch with Harold Hughes, the former Iowa governor and Senator who quite politics to devote his life to Christian work. Barron and Hughes, both reformed alcoholics, first met when they both were governors.

Barron said he doesn't know Marvin Mandel, "but my heart goes out to him." Reflecting on the political life. Barron said it is "sad that it takes so much money to get elected" to high office.

"A candidate can lose control over who is working for him, and what promises are being made in his name," Barron said. "You are elected, and sitting in that big office, and soon a fellow comes in and says, 'I did this for you and now I expect. . ."

"Corruption doesn't have to follow, of course," Barron said. "The man (office holder) doesn't have to get involved. There has to be a weakness there."

Barron is introspective about his own downfall. "Had I stopped as attorney general," he said, cursing his ambition. "I'm as certain as a reasonable man can be about anything that I would have returned to Elkins (his hometown) and lived a life of serenity. I never would have been incarcerated. I wish to heaven I had lost that election."