Fannie Mae and Freddie Mac have drummed up little support for their controversial proposal to pay mortgage servicers a flat fee for performing loans, but one top-tier lender has stepped forward to publicly endorse the idea. Ally Financial in a comment letter to the Federal Housing Finance Agency said it supports the so-called fee-for-service proposal, combined with a policy that would provide for the separation of excess interest-only cash flows from the underlying mortgage servicing rights. The company, which ranked as the fifth-largest servicer in the market as of the end of September, did...