Fannie and Freddie - Secondary Market Audits

Hello, 

Our credit union recently began selling loans directly to Fannie and Freddie. The investors require an annual audit of Secondary Market loans. In the past, we've conducted mortgage audits of our in-house portfolio loans. Is anyone a direct seller to Fannie and Freddie? If anyone has an audit plan that is specific to secondary market loans or has a good mortgage audit workplan, would you be willing to share it with me? [email protected]. 

Thank you!