Just when you thought you knew everything about our hero, here's some insider trivia that will astound and amuse.

If history had gone just a tad bit differently, we could be getting ready to watch Tom Selleck reprise his most famous role -- professor of archaeology, expert on the occult and obtainer of rare antiquities Indiana Jones -- in "Indiana Jones and the Kingdom of the Crystal Skull," which opened in theaters on Thursday.

That other guy -- Harrison Ford? Well, maybe he'd be on "Boston Legal" right now. Maybe he would have had a good run playing Monica's love interest on "Friends."

"They've been enormously important for the longevity of my career," Ford, 65, said of the "Indy" movies. "I've been living off them ever since."

He's not exaggerating. Looking back, the only major player on solid ground when "Raiders of the Lost Ark" came out in 1981 was producer George Lucas, who was currently in the midst of his successful "Star Wars" trilogy. (The Ewoks hadn't reared their ugly, cuddly heads yet.) Spielberg was coming off a flop ("1941"). Ford had yet to prove that he could move beyond Han Solo.

"Raiders" changed all that. Spielberg's throwback to old-time adventure serials became the template for the summer action-adventure blockbuster, laying down a blueprint that has been pillaged and plundered by lesser filmmakers for the past quarter-century.

Given that 19 years have passed since Indy last cracked that whip, we thought a refresher course on our favorite fedora-wearing, ophidiophobic adventurer might be in order. Jones would be 58 when the action in "Crystal Skull" takes place.

But, as Indy himself once put it, "it's not the age, it's the mileage."

"Raiders of the Lost Ark"

Release date: June 12, 1981

Budget: $22 million

Box office: $209 million domestic; $141 million foreign. Highest grossing movie of the year in the States.

Lucas hot, Spielberg not: Studios didn't want Spielberg to direct "Raiders," viewing him as a spoiled, indulgent director responsible for the over-budget clanker "1941." Spielberg viewed "Raiders" as an opportunity to prove he could make a hit movie and be fiscally responsible. He succeeded on both counts.

"Magnum" Jones: Harrison Ford owes his career to the fact that CBS picked up the option on the pilot of "Magnum P.I." and refused to let Tom Selleck out of his contract. Lucas had cast Selleck over Ford, not wanting to use Ford again after the "Star Wars" movies and "American Graffiti."

"I was wary of Harrison and I becoming like Scorsese and De Niro," Lucas said.

With Selleck out of the picture, Spielberg went back to Ford, his first choice for Indy.

Good thing, because his cat is named Precious: Jones took his name from producer George Lucas' dog, Indiana.

Spielberg's two favorite scenes: The monkey doing the "Heil Hitler" salute and Marion kissing Indy in all the places "where it doesn't hurt."

Early "Terminator": Steven Spielberg originally planned for sadistic Nazi henchman Toht to have a prosthetic hand that housed a flamethrower and machine gun. Lucas nixed the idea, telling Spielberg he was jumping genres.

More casting: Spielberg wanted Danny DeVito to play Indy's sidekick, Sallah. Klaus Kinski was offered the part of Toht.

"As much as I'd like to do a movie with Spielberg, the script is as moronically (awful) as so many other flicks of this ilk," Kinski wrote in his autobiography.

Bigger bang: Indy was originally supposed to disarm the film's flamboyant swordsman with his bullwhip. But Ford had come down with food poisoning and couldn't perform the stunt. Someone casually suggested Indy should just shoot him, and Spielberg ran with the idea.

Phone home: During breaks in shooting, Spielberg and Melissa Mathison (then married to Ford) worked on a script about a space alien visiting Earth. "E.T.: The Extra-Terrestrial" would be Spielberg's next movie.

Critical reaction: Almost universal praise as well as eight Oscar nominations, including best picture. (It won four.)

Does it hold up?: "The first 'Indy,' for me, is the most perfect of the three," says Spielberg. "I've never gone back and said I could have done anything better than what I achieved on that film."

He's right.

"Indiana Jones and the Temple of Doom"

Release date: May 23, 1984

Budget: $28 million

Box office: $180 million domestic; $153 million foreign. Ranked behind "Beverly Hills Cop" and "Ghostbusters" at the U.S. box office that year.

Original title: "Indiana Jones and the Temple of Death." Too dark.

Apology offered: When Spielberg announced plans for "Indiana Jones and the Last Crusade," he said he wanted to "complete the trilogy" and "apologize for the second one." He blames the story -- which involved young kidnapped kids and nightmarish special effects -- for the film's failure.

Adds Kate Capshaw, the movie's damsel in distress who married Spielberg in 1991: "We had children at risk -- where's the fun in that? There were also 100 more screams than we needed."

Dames!: Lucas was going through a bitter divorce and Spielberg was having relationship woes, which Lucas says informed "Doom's" dark tone. It may also have had something to do with the grating whininess of Capshaw's nightclub singer, easily the weakest female character in the series. ("Iiiindeeeeeeeee!")

Doubling Indy: Ford wrenched his back riding an elephant, forcing him to return to Los Angeles for treatment. Stuntman Vic Armstrong filled in for several weeks with Spielberg shooting him in costume from behind or at a distance of five feet.

New rating: Spielberg had been pushing the PG envelope with his own movies ("Raiders" was originally slapped with an R because of the face-melting finale) and those he produced. (Parents bemoaned those microwaved "Gremlins.") Outcry over the grisly heart-yanking scene in "Doom" led Spielberg to suggest a new "PG-14" rating. MPAA President Jack Valenti bumped it down and the PG-13 movie was born. ("Red Dawn" inaugurated the rating later in 1984.)

Critical reaction: "I don't think there was a good review," Capshaw told Empire magazine.

Does it hold up?: No need for a critical reappraisal. When Spielberg whiffs, he misses badly and the crass "Doom" stands with "Hook," "1941" and his episode in "Twilight Zone: The Movie" as the worst work in his great career.

"Indiana Jones and the Last Crusade"

Release date: May 24, 1989

Budget: $48 million

Box office: $197 million domestic; $277 million foreign. Ranked second at the box-office that year behind "Batman."

No more gloom and "Doom": Producer Frank Marshall maintains "The Last Crusade" wasn't a reaction to the darkness of "Doom," but the film's tone is deliberately light, mellower and a mile removed from the xenophobic, voodoo vitriol of its predecessor.

Daddy-no: Sean Connery initially turned down the role of professor Henry Jones, telling Spielberg he was too young to play Ford's father. (There's a 12-year age difference between the two actors.) But Spielberg, who had long flirted with doing a Bond film, won Connery over with his persistence.

Stoppard shines: Playwright Tom Stoppard did an uncredited rewrite. Spielberg says Stoppard wrote "every line of dialogue" in the movie.

Connery contributes: Connery was responsible for at least one line, though. When questioned how he knew Dr. Elsa Schneider was a Nazi, Connery ad-libbed, "She talks in her sleep."

Critical reaction: Tim Burton's "Batman" got all the buzz that summer, but "Crusade" proved Spielberg could still provide expert escapist entertainment.

Does it hold up?: "Raiders" may be more exciting, but the humorous interplay between Ford and Connery make "Crusade" a journey worth repeating.