In 2018, production of the Ram 1500 will move from its historic home in Warren, Mich., to Sterling Heights, 10 miles north. At 5 million square feet, FCA's Sterling Heights plant is half-again as big as the Warren plant and much more modern.
A large SUV would be a first for Ram, which was calved from Dodge in 2009.
Details such as powertrain specs aren't yet available, but AutoPacific analyst Dave Sullivan said a Suburban fighter would solve a bigger issue.
"It's a real no-brainer when you look at potential profit margins, but CAFE requirements are looming," Sullivan said. "Marchionne has been looking for a new currency printing press and an SUV based on a pickup is a relatively easy solution, from a development and investment perspective."
Marchionne said a Ram SUV wouldn't compete with a planned three-row Jeep Grand Wagoneer.
The Grand Wagoneer, whose development has been delayed until 2019, would be a luxury vehicle competing with Range Rover.
"I don't think anybody who buys a large SUV is confusing it with a Range Rover," he said.
Large SUVs are among GM's most profitable vehicles and huge contributors to the company's double-digit North American profit margin.
Sales of large SUVs were down 1.9 percent through the first nine months of 2015 but still represented almost 390,000 vehicles, according to the Automotive News Data Center.