FLINT, MI – General Motor Co.’s manufacturing chief says a heavy-duty pickup plant here is on the brink of moving to three shifts and joining a growing number of the auto maker’s North American facilities running at or near capacity.

“We’re running hard out here,” says Larry Zahner, manufacturing manager at GM. “We think at some point in time we’ll be on three shifts.

“It’s all market demand, but the (HD pickup) market is moving very well for us right now,” he tells Ward’s on the sidelines of an event earlier today commemorating the 13 millionth vehicle to come out of the historic Flint Assembly plant, located an hour north of Detroit.

GM’s large-pickup sales so far this year are up 11.9%, according to Ward’s data, compared with an overall industry that is 8.4% ahead of last year’s pace. Heavy-duties typically comprise 30% of large-pickup sales. GM’s overall sales are up 6.3%.

Flint assembly currently operates two shifts with “plenty of overtime,” Zahner says. It is GM’s only pickup plant in North America tooled to build the Chevy Silverado HD and GMC Sierra HD crew-cab models that are in hot demand right now.

Flint makes only a handful of light-duty pickups, about eight units every day. Fort Wayne, IN, handles most of GM’s light-duty pickup demand and also builds heavy-duty models, but a lack of space limits the facility to regular- and extended-cab production.

One pickup plant simply can’t accommodate all the parts necessary to build three body styles.

GM shuttered pickup plants in Pontiac, MI, and Oshawa, ON, Canada, with its bankruptcy, consolidating production at Flint and Fort Wayne. A plant in Silao, Mexico, builds light- and heavy-duty models for local consumption.

Zahner says building specific body styles at specific plants still gives GM the flexibility it needs in the pickup market, where demand can fluctuate between regular-, extended- and crew-cab models.

GM has not yet reached the pinnacle of flexibility, where a single assembly plant builds vehicles from more than one platform, but wherever one vehicle gets built a platform-mate could be assembled on the same line.

“It starts with the holes in the frame,” Zahner says, pointing to the auto maker’s Delta Twp. MI, plant, where three products are built off the Lambda large cross/utility platform. “If the holes are in the same place, we can built it.”

Someday, he says, the approach could accommodate different platforms, but as with the pickup body styles the body shop presents a big hurdle because of the proliferation of parts.

Paint shops can accommodate a variety of vehicles, too, because robots can be programmed to paint any contour, but most are sized for the product they originally were intended to build.

“It’s a long strategy,” Zahner says of GM’s 10-year-old plan for flexibility. “But we’re getting to where we’ll be able to produce exactly what we did before with fewer plants.”

If Flint went to three shifts, it would join GM plants in Ingersoll, ON; Delta Twp.; Fort Wayne; Lordstown, OH: and Fairfax, KS; in running at capacity. Arlington, TX, also teeters on the verge of full capacity, operating two shifts, plus two of every three Saturdays.

“That’s where we want to be,” Zahner says. “We want to run all out on three shifts. That’s what makes the auto industry strong.”

An Onyx black Sierra Denali HD dually crew cab rolled off the line here earlier today, marking the Flint facility’s 13th millionth vehicle build.

With more than 63 years of production, Flint has built 4 million cars and 9 million trucks, including the first Chevy Corvette, the Bel-Air, Chevelle Malibu and medium-duty Top Kick trucks.

Flint is the birthplace of GM and the United Auto Workers union.