The Iowa Leading Indicators Index remained at 106.1 in March, the Iowa Department of Revenue said yesterday. That was unchanged from January and February after holding at 106 from October to December. Four of the eight index components contributed positively: the Iowa stock market index, average weekly manufacturing hours, diesel fuel consumption and average weekly unemployment claims. Negative contributors were the national yield spread, the new orders index, residential building permits and the agricultural futures profits index. The index was constructed to have a value of 100 in the year 1999.