WASHINGTON (AP) — Two senior Treasury officials say they had never seen a loan restructuring similar to an Energy Department loan to a failed solar panel maker.The half-billion dollar loan to Solyndra Inc. was restructured so that private investors moved ahead of taxpayers for repayment on part of the loan in case of a default.Asked by Republican members of Congress if they had seen that occur in a federal loan, Treasury officials Gary Grippo and Gary Burner said no.Grippo is a deputy assistant treasury secretary and Burner is chief financial officer at the Federal Financing Bank, which made a $528 million loan to Solyndra in 2009.The two men stopped short of declaring the loan restructuring illegal, as Republican allege.