ByJohn S. McClenahen A second look at this year's second-quarter productivity produced positive results for U.S. manufacturing. Revised data from the U.S. Labor Dept. show productivity rising at an annual rate of 1.1%, entirely the result of a 1.7% productivity gain among makers of autos, appliances, airplanes, and other durable goods. Output per hour, the government's measure of productivity, was unchanged in the nondurable-goods sector. Previous Labor Dept. data had shown second-quarter manufacturing productivity declining at a 0.2% annual rate. For the non-farm business sector of the U.S. economy, revised numbers show second-quarter productivity advancing at a 2.1% annual rate, nearly half a point slower than the 2.5% reported a month ago. "Nevertheless, U.S. productivity remains quite healthy given the tepid economy," says Bruce Steinberg, chief economist at Merrill Lynch & Co., New York. He's looking for a 2.5% rate of productivity growth in this year's third calendar quarter -- and further acceleration in 2001's final three months.