In the last 40 years only one man in baseball has had more than 400 total bases in a season - Stan Musial with 429 in 1948.

In 1959 Hank Aaron had 400 on the nose. Since then, nobody.

Willie Mays, Mickey Mantle, Ted Williams - name them until your names turns blue - none of the other greats of the last 40 years ever got close to 400 total bases, a mark that ranks close to a .400 batting average in its rarity.

Now, in the closing weeks of this year of fabulous hitting, a slugger is closing in on the magic 400; he already has 352 total bases with three weeks to play. If he keeps up his hot pace of the last two months, he'll get there.

For 400 total bases you have to do something - have well over 200 hits, bash more than 40 homers, get gobs of triples and never miss a turn a bat.

Who is this superman?

He is Jime Rice of the Boston Red Sox, who finished 12th at his position in the all-star balloting and can't win a starting a job on his own team.

Thogh Aron singles him as "the only active player who might have a good chance to beat my 735 career homers," he is far from being the most famous player on his own team.

Rice has a knack for avoiding the spotlight.

Rice, who somehow manages to get overlooked in discussions of Most Valuable Player - over on his own team - already has 185 hits, 24 doubles, 14 tripples and 38 home runs.

He leads the league in homers b four, in total bases by more than 40 and in slugging average (.612) by nearly 50 points.

In addition, Rice is second in the Al in runs (96), RBI (105) and triples, while batting .322.

How has this man stayed in hiding so long?

He leads the Red Sox almost everything, including game-winning hits (13), and is a terror with men on base, hitting .329 in those situations.

Yet Rice has never been rightly puffed for two reasons - his stolid, sometimes suspicious and with-drawn nature and his man-with-no-country status as a designated hitter.

Rice is from rural Anderson, S.C., and returns there in the offseason to the down-to-earth people he enjoys most. Big city life and glamor don't appeal to him. A few gold necklaces, rings and watch are his only outward signs of allluence.

Though he is 24 years old and in his third full year as a star, Rice is just as tight-lipped toward the world outside the locker room as he was in 1973 when fellow Red Sox rookie Fred Lynn got the bulk of their Dynamic Duo publicity.

"Jim is very stable, even a little fun-loving around the team," says one regular Boston writer, "but he protects himself against the outside world. It's hard to get him to loosen up and talk naturally."

How long would such a project of getting acquainted take?

"Better set aside about a year," said the writer.

In fact, Rice can be almost gregarious if the subject is the mental aspect of hitting.

"Hitting is mostly in your head," says the 6-foot-2, 205-pound all-sport standout who once stapped a bat in half by trying to check his swing. "I have devoted myself totally to hitting this season. I've wanted to see what I could do if I committed all my energies to one thing.

"When you're going like I've been this year, it almost starts in the morning when you wake up. It's a sort of trance that you're in all day.You carry that grooved feeling with you."

Baseball insiders have wondered since the first day Rice hit the majors what his production would be like if he finally found that invincible, locked-in feeling that all great hitters carry with them to the plate.

As a 22-year-old rookie, Rice hit .039 with 102 RBI despite missing the last dozen games of the season and the attention-getting playoffs and World Series due to a broken wrist. That was the beginning of Rice's apparent genius for avoiding notoriety.

Last season Rice tried to increase his home run output from 22 to somewhere around 75 - the level folks said he ought to be at if he played all those games in Fenway.

The combination of Green Wall fever and pique over having to split his time between left field and DH knocked his figures down to a modest .282, 85 RBI and 25 homers.

This spring Rice made a vow. "I will do anything I can to help the team and I will hit .300," was his public summation of his entire world view.

This bland catchall really concealed a multitude of resolutions. "Help the team" meant stop worrying about those three gold gloves - Carl Yastremski, DwightEvans and George Scott - who happened to play the three positions - left field, right field and first base, where Rice was not too awful. If fulltime DH was the bottom line, then Rice would make the best of it.

The .300 goal marked a shift from his pull-hitting craze of 1976.

"I've discovered," said Rice earlier this year, "that all ball parks come equipped with a right field."

Ergo: stand farther from the plate, stride toward the dish and rip the ball to all fields, the way he did as a rookie.

The new stance and theory have eliminated Rice's glaring weakness - fast balls on the fists - while creating extra base (i.e., total base) possibilities in all corners of the park.

By ignoring the Green Monster, Rice has made it his friend. Of his 38 homers, 26 have been in Fenway Park.

The year has been both insular and productive. Like many a great player before him - from Ty Cobb to Roberto Clemente to Rod Carew - Rice has exploded in his third full year. It almost seems to be part of the Hall of Fame timetable.