"Dallas" lovers who tune in to the three-hour CBS movie "Dallas: The Early Years" tomorrow night at 8 on Channel 9 may be shocked to learn how the fine, upstanding Miss Ellie managed to snag Jock Ewing as her husband. "Dallas" loathers who last through a brief introduction by Larry Hagman and a somewhat slow beginning may be surprised to find an engaging tale of wild-catting and romance in 1930s Texas with an ending that's downright clever.

But no one should be startled by the film's revelation that the nefarious J.R. Ewing was conceived out of wedlock.

Ostensibly the story of the romance between the now-deceased patriarch and the remarried matriarch of the high-rated nighttime soap -- and the lowdown on the feud between the show's fighting families, the Barneses and the Ewings -- "The Early Years" is more successful in telling its rags-to-riches tale of adventure and lust than it is at sorting out mysteries that have kept Friday-night fanatics glued to their screens for the past eight years.

In fact, the movie's explanation of the beginnings of Ewing Oil and the rift between the Ewing brothers and Digger Barnes is inconsistent with the tidbits of that history that have been parceled out over the years on the weekly series.

Strong performances from Dale Midkiff and Molly Hagan as the youthful Jock Ewing and Ellie Southworth keep the western moseying along at a fast enough clip to retain the interest of any novice viewer. The movie is about the budding friendship between honorable Jock Ewing and the clumsy, drunken Willard (Digger) Barnes (David Grant) and how they strike it rich in oil. When they head back to the Southworth Ranch, where Digger has left the gal of his dreams, a predictable but eternal triangle develops to test the limits of their friendship and partnership.

It's engaging entertainment with special treats in store for "Dallas" addicts. It's fun to see dowdy and serene Miss Ellie as a feisty yet wholesome lass and crusty old Jock as a brooding young heartthrob, not to mention the obnoxious adolescent J.R. (Kevin Wixted) trying to nab a girl for a roll in the hay at the annual Ewing barbecue. Or a toddling Cliff Barnes leaving little Bobby Ewing in tears at the swing set as Barnes pulls his baby sister Pam off the swing and drags her home.

The saga isn't as glitzy or as zippy as the series, but times were simpler then. And maybe just a tad more civilized. As J.R. explains to a writer in the opening of the movie, "I told my Daddy, ' Digger Barnes is a drunk, a failure, a man that tried to kill you. Why don't you just snuff him out?' " If he had, of course, television history -- not to mention the story of Southfork -- would have to be rewritten.