By AMY WILSON | Automotive News Ford Motor Co. expects to run out of current-model Mustangs before it begins assembling the redesigned 2005 Mustang in September. Production of the 2004 Mustang will end May 10 at Ford's Rouge plant in Dearborn, Mich. Then Ford will shift Mustang production to Flat Rock, Mich., where it runs a joint-venture assembly plant with Mazda. Since August, Ford has been building Mustangs on overtime to help it through the summer production drought. But demand for the old model has surpassed expectations: Mustang sales are up 16 percent this year. "It's not going to make it," said Ford Division President Steve Lyons. "By July, they're going to be pretty scarce." Buoyed by overtime production, Mustang stocks have been high through the winter. But the numbers are coming down fast. Ford had 58,200 Mustangs or a 96-day supply on April 1, down from a 127-day supply on March 1. Sales for the rear-drive Mustang coupe and convertible typically are strongest in the spring and summer. Convertibles account for 30 percent of production. After the current stock of convertibles sells out, buyers must wait until spring 2005 to get a drop-top version of the redesigned Mustang. Ford offers a $3,000 cash rebate on the Mustang, but it might scale that back in May or June as inventories drop, Lyons said. "There's no point when you're going to run out," he said. "You can't just back it off to zero. That doesn't work, but you might dial it differently." ..glad to see it is selling well in the last year of fox...v6's run aroudn 12.5 after rebates around here, it's a solid value no doubt.