Stellantis invests $24.7 million to retool Michigan engine plant Stellantis invests $24.7 million to retool Michigan engine plant June 30, 2022 dzadmin Comments 0 Comment Stellantis said its Trenton engine plant will be retooled to a be flexible engine line able to produce the two variations of the 3.6-liter Pentastar V-6 engine.