Countrywide Financial Corp. said today that it has applied to change the charter of its bank unit to a federal savings bank charter. The conversion would allow Countrywide’s bank division to operate as a savings and loan under the Office of Thrift Supervision. Countrywide currently operates under a national bank charter. “In our continuous efforts to maximize efficiencies, the company has determined that Countrywide is better positioned for future growth as a savings institution with a single primary regulator as opposed to the current dual-regulator structure,” said Angelo R. Mozilo, chairman and CEO of Countrywide, in a statement.