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Gary Coleman, Conrad Bain and Todd Bridges at the 2003 TV Land Awards.

The death of Conrad Bain at age 89 has hit no one harder than Todd Bridges, who for eight seasons played adopted son to Bain's millionaire character Mr. Drummond on the hit NBC sitcom "Diff'rent Strokes."

Now the sole survivor of the show's core cast -- Dana Plato committed suicide in 1999, and Gary Coleman died after falling down a flight of stairs in 2010 -- Bridges says he'll miss the man who was his surrogate father both on and off the screen.

"This is probably one of the most heart-wrenching days I’ve had in a long time," Bridges, now 47, tells The Hollywood Reporter. "That Conrad’s not going to be around anymore to talk to. Whenever I needed advice, I’d call Conrad."

STORY: "Diff’rent Strokes" Dad Conrad Bain dies at 89

The two first met in 1977, when a 12-year-old Bridges -- who had already starred alongside Abe Vigoda on ABC's "Barney Miller" spinoff, "Fish" -- was cast with Bain and Coleman to star in a 20-minute presentation for NBC executives. The chemistry between the trio was so effortless, the network brass bought a full season on the spot.

"First time in history they bought 26 shows based on a presentation like that -- a balcony scene that me, Conrad and Gary worked on together," Bridges recalls.

"Diff'rent Strokes" was an instant hit with audiences, which Bridges partly attributes to the country's frayed social landscape at the time: "It was during a time that race relations were kind of poor in America, and it kind of hit home that it doesn’t matter what color you are. Whoever God puts in front of you is who you’re supposed to love," he said.

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Bridges and Bain instantly bonded, as they'd both regularly show up early to work -- and the fatherly Bain filled a void in Bridges' life.

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"He was a really good man," Bridges says. "He really was like Mr. Drummond. Just an all-around nice guy. He treated me better than my own father treated me."

The ensuing years brought plenty of turmoil for the show's young stars, including Bridges' much-publicized addiction to crack cocaine in his 20s and an arrest for the murder of a drug dealer, for which he was later acquitted. Through it all, Bridges says, Bain was there to offer a sympathetic ear and his advice.

Eventually, Bridges got clean and had a family of his own, beginning with son Spencir Bridges -- at 15, now a busy working actor who has appeared on episodes of "House M.D." and "iCarly" and in the 2003 Eddie Murphy film "Daddy Day Care."

"When I had my son, I took him to Conrad's house and he loved him, played chess with him, called him his grandson," Bridges says. "He just really knew how to take care of people."

"I cried all day. I can’t even cry anymore. I'll truly miss that man," he adds.

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Actor Conrad Bain, perhaps best known for his role as kindly millionaire Phillip Drummond on "Diff'rent Strokes," has died at 89, his daughter, Jennifer, has confirmed to Access Hollywood.

Everett Collection

Conrad Bain, seen with the cast of "Diff'rent Strokes" in 1978, has died at age 89.

Bain had been hospitalized since Thursday, Jennifer Bain said, and wasn't suffering from an illness. 

"He just died of old age," she told Access Hollywood.

Bain also said that she and her brother were with their father when he died, and that she sang to him in his final moments.

Bain's daughter said she "adored" her father "as did many others that knew him. A whole generation of people saw him as a father, so I just want to share in their loss."

There will be no funeral or public memorial, she said. 

Todd Bridges, who is the only survivor among the three young actors who played Bain's children on the show, had kept in touch with Bain and spoke with him just a week ago, he said, calling Bain "the glue" of the cast.

"I am deeply saddened by the sudden passing of Conrad as we were looking forward to celebrating his 90th birthday next month," Bridges said in a statement. "In addition to being a positive and supportive father figure both on and off-screen, Conrad was well-loved and made going to work each day enjoyable for all of us. He will be missed, but never forgotten."

Bain had already played a major role on the 1970s sitcom "Maude" when he was cast on "Diff'rent Strokes." He played a wealthy Park Avenue widower who adopted the two black sons of his deceased housekeeper. The show made a star out of young Gary Coleman, whose catchphrase "Whatchoo talkin' about, Willis?" became a national sensation. The show also produced a hit spin-off, "The Facts of Life."

But the show had its share of troubles. Young stars Coleman and Bridges, who played Drummond's adopted sons, and Dana Plato, who played his daughter, would struggle with drugs and legal woes. Plato became pregnant during the show's filming and was dismissed from the program. She later committed suicide.

Coleman, whose growth was limited due to an autoimmune disorder, struggled financially and professionally, and died at age 42.

"Diff'rent Strokes" ran from 1978 to 1985 on NBC. It was canceled for low ratings and then picked up by ABC for one final season, ending in 1986.

On "Maude," Bain played title character Maude's neighbor, Dr. Arthur Harmon. Bain's own real-life twin brother once made an appearance as Harmon's brother.

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Related content:

• Singer Patti Page dies at 85
• Mothers of Invention singer Ray Collins dies
• Slideshow: Lost memories of the '70s and '80s