If life begins at 40 — which it did for Mel Brooks, when he started writing his Oscared screenplay for "The Producers" — then the kidder from Brooklyn is well into his second life.

In 2001, at age 75, Brooks became a born-again Broadway baby, literally taking a sharp right turn into another medium by retooling and tuning up his screen-shtick oeuvre for the Main Stem. Songs (or, more accurately, musical parodies) had always been a part of his movie comedies — in 1974 he was even an Oscar-nominated lyricist for the title tune of "Blazing Saddles" — but this new self-assignment meant writing the score for a whole show.

To say he came through with flying colors is to call The Johnstown Flood a slight drizzle.

His debut entry in this rarefied field — The Producers, with Nathan Lane and Matthew Broderick honoring the film memory of Zero Mostel and Gene Wilder — became Broadway's 18th longest-running show (racking up 2,502 performances before departing) — and, to date, its most acclaimed. It swept the Tony shelf clean, winning all it was up for (12 awards, more than any other show). With overlaps in the acting categories, the show is also the most Tony-nominated (15 in all).

It's good to be the King of Broadway, apparently, for here he comes again — a spry, sprite-like 81, remarkably unbowed by the enormous pressure of having to top himself (both by all he achieved in paragraph four and by his original screen creation, "Young Frankenstein"). "Young Frankenstein" was Brooks' other Oscar nomination in 1974; he and his title player, Gene Wilder, were up for Best Screenplay Adapted from Other Material. When they started their Karloff takeoff, Brooks says, "we ran off all the old Universal monster movies. For months and months, all I saw was James Whale movies. He did the original 'Frankenstein,' 'The Bride of Frankenstein,' 'Frankenstein's Second-Cousin,' all of 'em."

Brooks also toiled in the eccentric workplace that Ken Strickfaden designed for the first (1931) film — full of electronic zaps, bubbling liquids, multi-shaped test-tubes — and, in the credits, he even thanked him for the use of the lab. "We copied Strickfaden's design and made something more gargantuan." Similarly, set designer Robin Wagner has been given a healthy portion of what has been said to be a $20 million budget to make sure the lab fits into Broadway's think-big M.O. and the cavernous Hilton Theatre.

"Robin knows what the needs of the piece are and provides them in spades. William Ivey Long has outdone himself — the costumes jump from lederhosen to swank, '30s Art Deco duds. And a guy named Peter Kaczorowski has lit the damn thing like a 1930s film."

This design team is one-fourth of the (Tony-) winning team of The Producers. Also returning: Brooks' script-collaborator, Thomas Meehan, and director–choreographer Susan Stroman. "Stro is as close to a theatrical genius as you'll get. She knows what the audience cries for, and she provides it beautifully. She understands the word thrill."

Brooks says he's in daily touch with his first Young Frankenstein and co-scripter, Wilder. "I don't do anything till I sing Gene the songs. He loves that this is becoming a musical."

Brooks has done 18 songs (more coming — or going — right up to the Nov. 8 opening). "I'm proud of the score's diversity." It's a musical checkerboard, like The Producers — a little Cole Porter here, a little Rudolf Friml there — plus bona fide Irving Berlin ("Puttin' on the Ritz," a little soft-shoe shuffle from Monster and Creator) and Victor Herbert ("Ah, Sweet Mystery of Life," a sort of eureka high-C to go with The Big O The Monster gives the doc's fiancée).

The one unduplicable thing in this reconfiguration is the brain-burning brilliance of the film cast: Wilder; Madeline Kahn as his fussily frigid fiancée, Elizabeth; Marty Feldman and Teri Garr as his hunchbacked and top-heavy assistants; Cloris Leachman as a Teutonic terror of a housekeeper, Frau Blucher, whose very name makes horses whinny; and Gene Hackman as the blind, dangerously hospitable hermit The Monster meets in his shuffles.

Nevertheless, the cream of the current Broadway crop came forth to fill those big shoes. Brooks is delighted: "It's like the Yankees of Babe Ruth and Lou Gehrig. Everybody who gets up to the plate gets a resounding hit. I couldn't ask for a better cast. We're blessed."

The remaking of Young Frankenstein, from screen to stage, was a three-and-a-half year "snap" — despite, or maybe because of, the heavy foundation work. "We're serving two gods here," Brooks explains. "It's very difficult to be faithful to all the iconic material and still put in new stuff. Musical comedy has certain demands, and movies have certain demands. When they marry each other, that's fine. When they don't, we go the musical comedy route. This isn't lightning strikes twice. It was long, hard work, rewriting, fine-tuning."

In the midst of it all was a deep personal tragedy — the illness and death of Anne Bancroft, 40 years his wife. The great actress and the great clown were Hollywood's most improbable (but enduring!) pairing, and the loss devastated him. Eventually, the work pulled him back into focus, back into life.

"Work," he says, "is the great source of peace, comfort and satisfaction — and there's nothing like working in what you love to do."