Even if Ford Motor Co. loses only a day or two of production of 2008 F-Series Super Duty trucks, March sales will be hurt, the automaker said.

Orders from dealerships for the Louisville-built truck have been stronger than expected and the vehicles that were on lots last month didn’t stay longer than six days on average.

At the end of the month Ford had only 12,000 of the trucks available for sale.

“The units that we have out there are turning quickly,” Ford sales analyst George Pipas said today. He added that there aren’t enough trucks in inventory to keep up with sales and that the few days of lost production will hurt.

Ford’s Kentucky Truck Plant on Chamberlain Lane worked partial shifts today and is scheduled to be down tomorrow. The company hopes to get full production up next week now that Navistar International has been ordered to resume shipping diesel engines to the plant.

Navistar on Monday announced it had stopped shipping engines to the plant because of a dispute over payments from Ford.

Pipas said the work stoppage did not affect February sales, but he expects to see an impact this month.

In February, Ford sold 55,251 F-Series trucks. Pipas did not release Super Duty figures, but they typically make up about 40 percent of the truck line’s sales.

F-Series sales fell 12 percent in February, an improvement from the 14 percent decline in January.

Ford sued Navistar in January, saying the engine maker failed to pay for its share of recalls on the 6-liter diesel engine sold in 2002-2007 model year Ford trucks. In its suit, Ford said it was withholding funds for the new 6.4-liter engine to recoup those expenses.

Late yesterday, a judge in Michigan issued a restraining order, forcing Navistar to restart engine production and Ford to restart full payments.