General Motors Co. said it will spend $328 million to upgrade its Flint, Mich., assembly plant. The plant overhaul is part of the company’s strategy for launching its next generation of full-size pickup trucks. The company says the move will save or create 150 jobs.

The factory, which builds heavy-duty versions of the Chevrolet Silverado and GMC Sierra, currently has 2,047 employees. GM said strong sales of the trucks, which were new for the 2011 model year, have boosted GM’s share of the heavy-duty market by 2.4 percentage points to 36 percent. The company said its retail share of the full-size pickup market has grown to 40 percent through May compared with about 38 percent in the first five months of 2010.

GM said the latest plant-improvement plan is part of $2 billion it is spending to create or retain about 4,000 jobs in 17 facilities across eight states during the next 18 months. For truck fans, the move confirms that large pickups are still a critical part of the vehicle market.

The Flint plant is among many GM facilities in Michigan that have benefited from the current round of major improvements totaling about $744 million. Others include the Flint Engine plant, Bay City Powertrain, Detroit-Hamtramck Assembly, Lansing Grand River Assembly, Saginaw Powertrain and GM Components Holdings in Wyoming, Mich.