AIN'T NOTHIN' AS SWEET AS MY BABY The Story of Hank Williams' Lost Daughter By Jett Williams with Pamela Thomas Harcourt Brace Jovanovich. 338 pp. $19.95

GET TO THE HEART By Barbara Mandrell with George Vecsey Bantam. 392 pp. $19.95

JETT WILLIAMS's and Barbara Mandrell's autobiographies, one from an aspiring princess, another from a reigning queen in the country music industry, make fascinating studies in down-home egomania. But one's a lot more engaging than the other.

Most Hank Williams fans who read his daughter's Ain't Nothin' as Sweet as My Baby out of curiosity about their idol will, I suspect, be frustrated. Though the mysteries surrounding the legendary Williams's intensely creative and intensely chaotic life are at the center of his illegitimate daughter's story, she's not writing about him. She's writing about herself -- her convoluted history as an adopted child and her legal and emotional battles to assert herself as one of Hank Williams's heirs. By the end of her story, Williams himself remains a puzzle.

One thing, however, does become crystal clear. This is the suingest little gal you ever didn't want to look at cross-eyed. Though Jett Williams, formerly known as Cathy Louise Deupree (her mother, Bobbie Jett, was Williams's mistress), tells us that her adoptive parents, the Deuprees, treated her to a prosperous middle-class lifetstyle, she's not overcome by gratitude. Indeed, she goes out of her way to spill venomous ink on her alcoholic, pill-popping adoptive mother, Louise. Yet when she had the temerity to leave her money to a blood relative instead of Cathy, Baby Jett, as her special friends call her, took the matter to court.

And that's only the frosting on her multi-layered legal cake, so to speak. Before suing her adoptive mother's estate, Baby Jett had already taken on the executors of the Hank Williams estate. As she tells in her book, she pursued the matter with awesome tenacity. That included marrying Keith Adkinson, the high-powered Washington legal eagle she rounded up to act as her knight-errant in the battle.

One can't help feeling a little sorry for the hapless college-sweetheart first husband and the adoptive parents caught up in the gears of this obsessive quest for identity and inheritance. Baby Jett describes the way she treated her first husband thus: "I would talk to Michael occasionally on the telephone, and told him that 'the work' was going well and I could not say when I would be coming home. The truth, of course, was that I knew I would never be 'coming home,' but I didn't yet feel ready to spell that out to Michael."

In Jett Williams's prologue she promises the reader "a great story -- replete with lust, passion, greed, betrayal, fraud, rejection, terror, lying, cheating, deceiving, tears, loneliness, despair -- and most of all, love lost and love found." It's true that her plodding narrative contains these elements, but they are often smothered in boring self-pity, gratuitous adoptive mother-bashing, and far too many numbing passages stuffed with forgettable family names and histories. "But for me, money was never the issue," she claims as she concludes her litigious saga. "Justice, blind justice was my cause -- from the start." Okay. BARBARA MANDRELL spent many of her growing-up years in California. But you'd never guess it if she didn't tell you. You can take the girl out of the country, but you can't take the country out of the girl -- not when there's any possibility of record royalties or a TV special in the offing.

Reading Barbara Mandrell's sprightly Get to the Heart is a little like plunking yourself down for an afternoon's perm under the busy hands of a fiercely talkative beauty operator. Mandrell gabs non-stop through her autobiography, determined in this gossipy, chipper tour de force to tell you everything and anything, so long as it relates in some way to herself.

Mandrell on family: "I was a daddy's girl when I was growing up, and here I am crossing forty and I am still a daddy's girl."

Mandrell on spanking: "I feel spanking is a form of loving and training your child."

Mandrell on the problem of evil: "I also don't believe God looks down and says, 'Zap! I'm going to give that person a heart attack.' That's the way it is. There are these things, germs, diseases, accidents in this life."

Mandrell on suicide: "To me, if a person commits suicide, that is the same as killing somebody."

Mandrell on men's hair: "I prefer short hair on a man. My theory is, if you're a man, look like a man."

Mandrell on wedding kisses: "I've been to weddings where the kiss went on and on, and I thought to myself, "Ooh, save it for later."

Beneath the frothy chat lie some very sophisticated underpinnings. Coauthor George Vecsey provides Mandrell's reminiscences and soliloquies on career and family loyalties with point and forward movement by arranging them around the drama of the car accident which, as she relates in detail, invalided her, paralyzed her career, and martyred her family for many months.

Like a steel rod running through whipped cream, the accident and its ramifications give Mandrell's story weight. They also create opportunities for her to make some surprising revelations. For instance, her erratic behavior during recovery included vile language which shocked her family -- "it surely was a revelation to me what kind of garbage and bad behavior floats around in your mind." Later, discussing the other discomforts which an invalid is heir to, she reveals that "Every night I would pray to get rid of the gas."

Indeed, Mandrell is endearingly frank. She even talls us that her husband fell asleep after making love to her on their honeymoon night and that she spent much of the rest of that night in tears. Yet I have to suspect that her homespun just-little-ole-me revelations are as carefully choreographed as her shows. This is a very professional lady who knows how to please her audience. People who are interested enough in Barbara Mandrell to want to read her story will probably love this book.

Louise Titchener is the author of over 30 published novels. Under the pseudonym of Jane Silverwood, her trilogy, "The Byrnside Inheritance," will be published early next year.