Overseas Shipholding Group Inc.'s warning that it may file for bankruptcy protection has companies that lease ships to the world's No. 2 tanker operator scrambling to find alternative customers and writing down the value of their OSG contracts, Reuters reported yesterday. Nearly 35 percent of OSG's 112-vessel fleet is leased, with contracts ending between 2013 and 2018. OSG, which has a stock market value of about $36 million, said last week that it was evaluating options including filing for bankruptcy protection as a result of a tax issue that could force it to restate results for at least the last three years. OSG's main credit line, a $1.5 billion fully drawn facility, is set to expire in February, leaving it with few options other than to restructure, shipping and restructuring experts said.