Many people believe that the Sarbanes-Oxley Act of 2002 only applies to publicly-traded companies. This is not exactly true.
Two provisions clearly apply to non-profits. Those would be Section 802 (document destruction) and Section 1107 (whistle-blower protections). Here's an ABA article (not that ABA) that provides a nice overview of the issue.
Finally, NCUA's only real guidance concerning SOX and federal credit unions is Letter to Federal Credit Unions 03-FCU-07. The guidance does not discuss the two provisions noted above, however.
It is probably worth noting that NCUA already has a whistle-blowing provision that protects credit union employees when they share information with NCUA. Here is that provision.