As a result of a surprise, targeted strike by the United Auto Workers union at Stellantis’ Ram truck manufacturing facility on Monday morning, 6,800 Stellantis employees walked off the job.

According to a statement issued by the United Auto Workers on Monday, Stellantis’ Sterling Heights Assembly Plant is one of its “largest plants and biggest moneymakers.” Based in Sterling Heights, Michigan, it produces Ram 1500 pickups.

Union officials said the company, which makes vehicles under the Dodge, Ram, Jeep and Chrysler brands, has “the worst proposal on the table” regarding pay, which includes converting temporary workers into full-time employees and cost-of-living increases.

While Stellantis has the highest revenue and profit margins, and has the most cash in reserve, it lags behind both Ford and General Motors in meeting the demands of its UAW employees.

The union’s decision to strike Stellantis’ largest plant seemed to catch the company off guard, as Stellantis believed negotiations were progressing.

“We are outraged that the UAW is expanding its strike action against Stellantis. Stellantis presented a new, improved offer to the UAW on Thursday morning,” the company said in a statement. “After multiple productive discussions, we left the bargaining table expecting a counter-proposal, but have yet to receive one.”

In the US market, Stellantis’ best-selling vehicle is the Ram pickup truck. During the first nine months of this year, the company sold 332,000 Ram pickups in the United States. However, it is not the only plant that builds the Ram 1500. Additionally, they are produced at a nonunion plant in Mexico, as well as at a UAW-represented plant in Warren, Michigan. Although Stellantis does not disclose how many pickups are produced at each plant, Sterling Heights is the largest.