General Motors' (NYSE: GM) plan to ramp up production of high-profit pickups has hit a snag: Short supplies of key parts from Mexico. GM, along with the other Detroit automakers, restarted some of its U.S. assembly plants on Monday. GM restarted its pickup factories in Fort Wayne, Indiana, and Flint, Michigan, with just one shift of workers at each plant as it worked through new safety procedures. GM had planned to add additional shifts next week, in an effort to get more of its highly profitable full-size pickups to dealers quickly. However, parts from some Mexican suppliers aren't yet flowing in sufficient quantities to support the added production, the Wall Street Journal reports. GM's assembly plant in Flint, Michigan, restarted on Monday. Image source: General Motors. The plan to add shifts has been delayed until June 1, says the Journal. While governments in the U.S. and Canada gave the Detroit automakers and suppliers approval to restart factories this week, Mexico's government has been more cautious. GM said yesterday that it had received approval to restart operations at two of its four manufacturing complexes in Mexico, and that it would do so as soon as possible. But it cautioned that its local suppliers may not be ready to support vehicle production in Mexico immediately. Those factories, in Silao, Guanajuato, and Ramos Arizpe, Coahuila, build some versions of GM's Chevrolet Silverado pickup and several of its crossover SUVs. Two other GM manufacturing sites in Mexico, in Toluca, Mexico State, and San Luis Potosí City, don't yet have dates to reopen, GM said. 10 stocks we like better than General MotorsWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and General Motors wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of April 16, 2020 John Rosevear owns shares of General Motors. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source