Some of them tell you in their guide how to code the loans they purchase. I think it is SunTrust that tells you to use 7, which I agree with. Itis not the bank itself buying the loan but an affiliate, a subsidiary of the bank.
Sometimes things change. I believe it is Wells that used to be a 7 but now it is the bank itself buying. Those contracts and investor guides are important. What legal entity is buying the loan?
I consider Franklin American Mortgage Company to be a 7.
https://franklinamerican.com/ext/general?npage=aboutUsFranklin American Trust is not to my knowledge the same company. It is listed by the Fed on the NIC site as inactive.
NIC does not necessarily list every investor. "About the National Information Center (NIC)
The National Information Center (NIC) provides comprehensive information on banks and other institutions for which the Federal Reserve has a supervisory, regulatory, or research interest including both domestic and foreign banking organizations operating in the U.S."
The banking institutions coded as "6" are deposit taking institutions. Enter commercial bank as entity type and choose a city name and see what you get. You,will see what I mean. Same with savings banks and savings and loans.