Pat Boone's parents are not crazy about the new musical direction their 62-year-old son is taking with "Pat Boone in a Metal Mood: No More Mr. Nice Guy." "Noooo! When I played them the rough mixes at home -- and it had to be loud -- Daddy and Mama were sitting there shaking their heads with glum looks because this is not the way they envision me singing or recording," Boone said recently from his home in Los Angeles. "Daddy wears a hearing aid in both ears, and at first he turned them down. Then he took them out."

Daddy Boone is 90, Mama Boone 86, and one suspects their eyes must have popped during Monday night's American Music Awards when Pat -- good old milk-drinking, clean-living, straight-arrow Pat, grandfather of 15 -- came out to present the hard rock/heavy metal award with Alice Cooper and out-Aliced the shock- rock veteran. Shirtless, decked out in leather pants and vest, sporting a choker, studded bracelet and dangling dragon earring -- and tattoos -- this person did not look remotely like Pat Boone.

And the white bucks?

They'll be on Boone's feet Friday on "The Tonight Show," but the singer says he's had five different black leather outfits made for that appearance. Those same white bucks can be spotted on the back cover of "No More Mr. Nice Guy" (an Alice Cooper anthem), as a shades- sporting Boone sits astride Big Bertha, a classic Harley-Davidson motorcycle.

What the heck is going on here?

Even Pat Boone wonders. It's a "bizarre thing that I've done."

The album, released this week, boasts Boone's big-band versions of a dozen hard-rock and heavy-metal tracks. These are songs made popular by Metallica ("Enter Sandman"), AC/DC ("It's a Long Way to the Top"), Ozzy Osbourne ("Crazy Train"), Led Zeppelin ("Stairway to Heaven"), Guns N'Roses ("Paradise City"), Judas Priest ("You've Got Another Thing Comin' ") and Deep Purple ("Smoke on the Water").

Until a few years ago, Boone, a former teen idol who has a weekly gospel show on the Christian Broadcasting Network, was

denouncing heavy metal as satanic. In a 1991 interview in the record collectors' magazine Goldmine, he singled out Judas Priest, AC/DC and Guns N'Roses for having gone "beyond degradation and depravity to inhumanity."

"This is true," Boone concedes. "I was very disparaging of even the term heavy metal' because it wasn't even human, so how could you convey human emotion?"

"No More Mr. Nice Guy" had its genesis five years ago when Boone was on a concert tour. In a late-night bull session with his band, he got around to the idea of doing something different, something he'd never done before. Well, he'd never done heavy metal.

And heavy metal had never been done big-band style. "Trombones, trumpets and saxes are metal, after all, and pretty heavy metal in the right hands," Boone points out helpfully. "The idea was to take good metal songs in a direction no one's ever heard."

And that's when Pat Boone, whose chart-toppers have included "April Love" and "Love Letters in the Sand," found himself listening to what he once condemned as satanic verses.

"I didn't really know the songs or groups," Boone says. "All I'd done was put them down because of the impressions I had of the way they looked and the excesses that seemed to go along with the lifestyle, the distortion and anger in the music when I'd hear it going across the radio dial. It sounded so jarring, so unnerving, I just went right on to something else."

Incongruously, Pat Boone did most of his heavy-metal research while starring in "The Will Rogers Follies" at the Will Rogers Theatre in the country music mecca of Branson, Mo. Trapped doing 12 shows a week for nine months, Boone spent much of his free time in his dressing room, seriously listening to heavy-metal albums and cranking up his boombox. ("I now know that to appreciate this music, it's got to be loud. It's not background music.") He even went to concerts by Ozzy Osbourne and Alice Cooper, but hid the metal CDs from his wife, Shirley. It was as much because of the covers as the contents, he says.

"I don't believe a whit in astrology, but you can sure make a case for me being the Gemini classic split personality," Boone says.

Once the songs were chosen, they were cut with a 19-piece band that included jazz musicians Tom Scott and Chuck Findley, with guest spots from Richie Blackmore, Ronnie James Dio, Dweezil Zappa and Sheila E.

Boone is the first to admit the project started as a joke, "and that's what makes this so dangerous, precarious. I see the humor in it, of course, and I've been playing on the humor in it and yet expecting that when the record comes out, people will see I'm very serious about the music. We were respectful, tried to keep all identifying trademarks, and a lot of people have told me that for the first time they can understand the words."

According to Boone, there's already enough material for a sequel, "songs I love by Dokken, Aerosmith, Poison, Scorpions, Megadeth. I feel like I stumbled into King Solomon's mine."

Boone's old fans might suggest he's stumbled into a location of much greater depth, though he is quick to point out that he doesn't endorse "the extracurricular excesses that have characterized the metal lifestyle."

In fact, he went over all the lyrics with a fine-toothed comb. Most were okay. One small exception: Van Halen's "Panama."

"It's a great song about either a car or a girl," Boone explains, pointing to such lyrics as "I'm going to get her at the turn/ And take her home with me." "That was fine because I told myself I was singing about a car. Well, there's one line -- hit the on-ramp/ Straight into my bedroom' -- so I changed it to hit the on-ramp/ Nothing that she can't do.' And that parses and sounds the same. Nobody but Van Halen would probably know I'd changed anything, but for me it keeps it kind of clean," he says.

Even the mighty Metallica seems to see the humor in all this. At Sunday's rehearsal for the American Music Awards in Los Angeles, when Metallica was onstage in the Shrine Auditorium, "the sound man put on, real loud, the intro of my recording of Enter Sandman,' which is identical to theirs before the big band kicks in. And when it did, {guitarist} Jason Newsted and {drummer} Lars Ulrich clenched their fists in the air and went Yeah!' And when I started singing, a big broad grin came over {vocalist} James Hetfield's face, which was a great relief to me."

Pat Boone's prime, of course, had come and gone a decade or more before the members of Metallica were forged in their mothers' wombs. Born in Jacksonville, Fla., raised in Nashville, Charles Eugene Pat Boone (a descendant of frontiersman Daniel Boone) entered and won local and regional talent contests before getting some early national attention in 1954 by winning on "Ted Mack's Original Amateur Hour" three times.

By then, the "most popular boy" and president of the student body was already married, having eloped at 19 with his longtime sweetheart, Shirley (daughter of western singing star Red Foley).

After some failed singles for a Nashville label, his career prospects brightened in 1955 with a version of an R&B song, "Two Hearts, Two Kisses," by the Charms. Boone had no particular familiarity with rhythm and blues, which still for the most part had not spread beyond black communities and radio stations. But white artists were beginning to record black hits, and Boone gamely gave it a shot.

Real success came with the release of a version of Fats Domino's "Ain't That a Shame" that went to No. 1, though the grammatically conscious English major at first tried to record it as "Isn't That a Shame."

"After a few takes, everyone agreed it ain't working," Boone chortles, noting that "ain't" was later included in dictionaries as acceptable usage. This apparently pleases Boone, who transferred to New York's Columbia University in 1957, graduating Phi Beta Kappa a year later with a BA in English and speech.

Between 1955 and 1961, Pat Boone would make the singles chart 60 times, topping it six times. "I always thought it was going to fizzle out and it was just God's way of helping me work my way through college," Boone says. Yet in the '50s, only Elvis Presley was more popular, and Boone had more records on the charts than Little Richard, Chuck Berry and Buddy Holly combined.

The notion that a milquetoast like Boone had more hits than such legends is why he is unlikely ever to get into Cleveland's Rock and Roll Hall of Fame without paying the standard admission fee. It's something that bothers but doesn't seem to rankle Boone. A few years back, he addressed the problem in a letter to Goldmine: "The purists, the folks who really like the down and dirty, real and raunchy, original R&B/R&R, are not likely to appreciate my records or the part they played in the whole evolution of the music." He even suggested that some of those already inducted might not have been heard by Hall of Fame voters without his versions.

"What people don't understand is that Little Richard, Fats, the Charms, the Flamingos had already enjoyed success . . . in their world," Boone says. "And there was no way {white} radio was going to play the original R&B records in that era because it was alien, it was raw." With his clean enunciation and metronomic constancy, Boone served up that raw music in what he himself calls "palatable and acceptable music garb."

Wisely, Boone has never made any claims for himself as a founding father of rock-and-roll, instead making a case for himself as "a midwife, helping deliver at the birth of rock-and-roll."

There was also the Elvis Factor, and though the two charted near-parallel paths -- Boone made movies, and had his own books, magazines and merchandising, as well as his own television show -- it didn't take long before he was perceived by rock purists as "the anti-Elvis."

Married, with four kids and absent even the whiff of scandal, "I didn't fit the image of the rock-and-roller," Boone says, "particularly as the image kept evolving from Elvis to Jim Morrison to Jimi Hendrix and on and on. Jack Daniel's and mooning -- how did Pat Boone fit that picture?"

He was purely wholesome: In the film "April Love," Boone refused to kiss Shirley Jones on screen lest his wife get upset. He turned down a film with Marilyn Monroe because it would have revolved around an extramarital affair. He declined one television series because it was sponsored by a tobacco company, and the nonsmoking teetotaler didn't want to imply he condoned such habits. Boone's last significant hit was 1962's "Speedy Gonzales," but he'd already begun carving out alternate paths in the gospel field and, later, in country and pop. He and Shirley raised their four daughters, only one of whom went into the music business. (Debby Boone had a No. 1 hit in 1976 with "You Light Up My Life" and won a Grammy as best new artist.) The Boone family is, its patriarch admits, divided on his heavy-metal music. "Debby was the most concerned, felt it was a fool's errand and I was setting myself up for a huge horselaugh. Lindy, daughter number two, was all for it -- she's been pretty adventurous herself, teaches aerobics and line dancing.

"Shirley shared Debby's feelings, double, thinking it was some late midlife crisis and I was setting myself up for a fall."

Shirley's fears were compounded when the Boones got word that a news anchor in Jacksonville -- Pat's home town! -- had read a story about Boone's heavy-metal project on the air and started laughing, then couldn't get control of himself and had to leave the set as another announcer finished the segment.

"And Shirley said, See, they're laughing at you!'

"But when the music comes out, I think people are going to say Wow!' "

That seems to be the reaction to Boone: The Next Generation. "The grandkids love it," he says. "They, too, thought it was crazy and undoable but when they heard the Enter Sandman' demo, they were really gung-ho and now they're stoked by my being on the big rock stations and on television and in the papers. All their friends are saying, This is your grandfather?' "

To hear a Sound Bite from Pat Boone's album call Post-Haste at 202-334-9000 and press 8171 for "Enter Sandman" or 8172 for "Paradise City." CAPTION: The new Pat Boone at the American Music Awards this week in Los Angeles and, above right, with wife Shirley and daughters Lindy, Debby, Cherry and Lory in 1960. CAPTION: Pat Boone as Mr. Nice Guy with his family: His new incarnation takes some getting used to.