The ongoing auto workers strike over at GM is dragging on into its fourth week and it’s starting to hit GM where it really hurts: pickup truck production.

Pickup trucks are big business. Not because they outsell other vehicle types--SUVs and crossovers are still bigger sellers. It’s because pickup trucks are enormously profitable. Pickups are big and simple lumps of metal that aren’t really more difficult or expensive to produce than a regular car, but they’re often priced way more than a family four-door sedan.

It’s said that much of GM and Ford’s current profits are coming from pickup sales, so if those sales were to stop, it’d really put a pinch in their pocketbooks.

That seems to be exactly what’s happening with the UAW strike. Without any workers, GM has been forced to close plants that create the Chevrolet Silverado and GMC Sierra. The Flint, Michigan facility that makes the HD versions of the full-size pickups shut down on the day of the strike (September 16th) along with the Fort Wayne, Indiana plant.

RELATED: Production Of The New 2020 Corvette Stingray Will Be Delayed Due To Ongoing UAW Strike

However, a new report from Automotive News says that the ongoing strike is also forcing GM to shut down plants that don’t even have UAW workers. Parts shortages caused by the strike have forced GM to shut down their Silao, Mexico site as of October 1st. That plant made the 1500 Silverado and Sierra pickups for the Mexican market, but they couldn’t keep making trucks without parts coming from the US.

Fort Wayne
via GM Authority

And the strike couldn't come at a worse time. Sales of the Sierra were up 39% in the third quarter of 2019, while the Silverado's sales were up 15%. Now, it seems unlikely that GM will make up for those losses even if the strike were to end tomorrow and production were to resume.

“I think you’re looking at a week, maybe two weeks, before dealerships are depleted and consumers have to make choices or wait on taking a delivery,” said Jeff Schuster, president of Americas operations and global vehicle forecasts for analytical firm LMC.

Since September, it’s believed that the strike has cost GM over $660 million in lost profits.

NEXT: UAW And General Motors No Closer To An Agreement As Negotiations "Take A Turn For The Worse"