NEW YORK ( TheStreet) -TheStreet Ratings' stock model upgraded Old Dominion Freight Line ( ODFL) to 'Buy' from 'Hold'. This $1.5 billion, less-than-truckload, freight delivery company doubled its second quarter net income to $21.5 million versus the second quarter 2009. TheStreet Ratings released rating changes on 30 additional U.S. common stocks for July 28, 2010. In total, just 11 stocks were downgraded and 20 stocks have been upgraded by our stock model. The number of upgrades exceeding downgrades by a two-to-one margin today can be credited to a positive second quarter earnings season being seen in our stock model results. Quarterly revenue at Old Dominion Freight Line reached $368 million, or 16.5% above its second quarter 2009 performance. Old Dominion President & CEO, David Congdon, cited improving trends in revenue and tonnage in the outlook for his company. Another company being upgraded by TheStreet Ratings' stock model is RPC ( RES), which moved to 'Buy' from 'Hold'. This oil & gas services company swung from a quarterly loss a year ago to a profit of $32 million in the second quarter. The company raised its dividend by 50% to 6 cents a share. -- Reported by Kevin Baker in Jupiter, Fla. For additional Investment Research check out our Ratings Research Center.