NBC's new six-hour version of "From Here to Eternity" is longer and dirtier than the 1953 Hollywood movie, but these are not exactly prize distinctions. It is an improvement over run-of-the-mill TV movies -- but that's more a reflection on the mill than on this extravaganza of lust.

The film airs in three two-hour chapters starting tonight at 9 on Channel 4 and continuing on consecutive Wednesdays. NBC calls it an "unabridged" version of the James Jones novel about people coming to the ends of their ropes at Pearl Harbor in the months preceding the Japanese attack there. "Unabridged" really means padded, poorly paced and repetitious.

In addition, "Eternity" has been somewhat upstaged on the air by Stirling Silliphant's "Pearl," the ABC mini-series that was set in the same period and also showed military officers behaving like swine and their wives sleeping around. To its credit, and thanks to the vigor of the original book and a capable TV cast, the characters in "Eternity" have considerably more vitality and depth, however.

NBC has also been bragging in its promotions that this time, the Jones novel is being told the way "Hollywood couldn't tell" it 25 years ago. Sometimes, however, discretion is the better part of art. There is a considerable difference in effect between the way Jones describes the alluring movement of a woman's breasts on the printed page and the way humdrum director Buzz Kulik zeroes in for a big fat closeup of Natalie Wood's bobbing bosom early in the first chapter of "Eternity."

It would be almost unpatriotic to object to such a shot, except that it establishes the central motif for a film that is not so much brutally frank as self-consciously ooh-la-la.

In part one we get lots of dialogue on the cutesy-smutsy side. "I once shot a man right where it stings," boasts Wood, lowering her eyes. "I wanna go to bed with you," pants William Devane. "You're good, but you're mechanical," says a customer to a prostitute. And all this leads up to a scene in which some top brass -- naturally, the most corrupt of all -- spend the evening with a gaggle of hired ladies, and Andy Griffith, as an especially smarmy old general, sashays off toward the bedroom with one on each arm.

The big beach scene ends the first part, except that it is no longer a beach, nor does the surf slosh as it once did so erotically (if hysterically) over Burt Lancaster and Deborah Kerr. Now Devane and Wood, in their roles, snuggle up in an inert lagoon; he takes down the straps of her bathing suit, does some quick necksmooching, and zap -- it's time for the inevitable freeze-frame.Still waters run dark and this is not quite the hotsy-totsy item publicity might have led one to expect.

Those who have not seen the original movie may find the new casting quite acceptable. Certainly Wood is uncommonly attractive and provocative, though what she would ever see in a moose as repulsive as Devane will be beyond almost everybody. Newcomer Joe Pantoliano makes a touchingly hapless Maggio, the part played in the movie by Frank Sinatra.

But the most fascinating presence and the one true asset of this television production is the quiet, mesmerizing portrayal by Steve Railsback of the phenomenally ill-fated Prewitt. Though hardly recognizable in his crewcut and khakis, Railsback is the actor who played Charles Manson in the CBS movie "Helter Skelter." As Prewitt he has a daringly subtle kind of intensity and a heartbreaking sense of resignation about the calamities bound to befall him. His performance is a spectacluar display of understatement.

Don McGuire's script, to judge from the first four hours of "Eternity," is basically straightforward and serviceable, but abridgement would do it no harm whatsoever, and director Kulik is so doggedly redundant that he shows us a flashback to Prewitt's last boxing match, when be blinded an opponent and thus quit boxing, and then repeats the very same information in useless exposition a few moments later.

The film is riddled with overstatement, restatement and scenes that last too long; to establish the fact that Fatso Judson (Peter Boyle, not nearly as good as Ernest Borgnine) is a brute in part two, Kulik and McGuire have him assault not just a couple of the prisoners in his stockade, but nearly a dozen -- over and over and over. This is the network television idea of telling the whole story, and it's the bunk.

'Make Believe Marriage'

The ABC television network gives about 14 hours of air time a year to programs that refute the idiot world view put forth in the network's hundreds of hours of prime-time Maypo. These refutations are called "Afterschool Specials" and the latest gem, "Make Believe Marriage," airs at 4:30 today on Channel 7.

"Marriage" deals with an older age group than the usual "Afterschool Special" -- high school students who enroll in a class called "Marriage in the Modern World" and, by pretending to be married, discover some of the practical pitfalls that await them should they decide to take the plunge for real. In the modern world, as it's called, the plunging seems to have become more and more accident-prone.

Writer Jeffrey Kindley and director Robert Fuest tell a beguiling little love story about a seemingly mismatched pair, played ultra-adorably by James Carroll and Janina Matthews, in the course of getting across the requisite wise counsel. Scenes of them picking out a baby (for their make-believe marriage) and gallivanting in a glen are especially swell, and the whole hour is another intelligent smash hit for this exemplary series.