UPDATE 1-Fiat Chrysler to invest $1 bln in Michigan plant, add 2,500 jobs

(Recasts throughout, adds reference to NAFTA, impact on other automakers)

DETROIT, Jan 11 (Reuters) - Fiat Chrysler Automobiles said on Thursday it will shift production of Ram heavy-duty pickup trucks from Mexico to Michigan in 2020, a move the automaker said was enabled "by the passage of U.S. tax reform legislation" in December.

The shift from Saltillo to Warren will create 2,500 jobs and cost $1 billion, FCA said. The Mexican plant will be "repurposed to produce future commercial vehicles" for global markets.

The United States and Canada are the principal markets for full-size heavy-duty pickup trucks, most of which are produced in the United States by FCA, General Motors Co, Ford Motor Co, Toyota Motor Corp and Nissan Motor Co .

U.S. President Donald Trump has threatened to force the rollback of the North American Free Trade Agreement, which enables the free flow of goods made in the United States, Canada and Mexico across the borders of those countries. Trump also has criticized automakers for moving jobs and investment in new manufacturing facilities to Mexico.

FCA Chief Executive Sergio Marchionne a year ago said the automaker could shift heavy-truck production from Mexico to Michigan, depending on the outcome of tax reform legislation and proposals to roll back NAFTA.

FCA on Thursday said it also would make a special bonus payment of $2,000 to about 60,000 FCA hourly and salaried employees in the United States. (Reporting by Uday Sampath in Bengaluru and Paul Lienert in Detroit; Editing by Maju Samuel and Matthew Lewis)