Thanks everyone.
@RatherBeGolfing, to answer you question, I think it is bits and pieces of everything you listed. I think there is some partial trust information, payroll records, etc., but not all the records (we have not personally been out to the client's physical location, so I cant speak for certain). It appears as though they just did not keep good records prior to 2016. They worked with a local payroll provider for a while (and they are in Alaska) and (I think), may have been doing a lot of their own plan administration (rather than using a TPA). Even when they worked with a TPA/REcordkeeper, the TPA "fired" them because they were not responsive to their request for information to complete annual testing, etc. (they were under a different owner, which has since changed and is why they are now looking to address all these issues). Unfortunately it does seem like a lot of the reason why information is not available is because the local payroll provider is no longer around (and hasn't been for years) and our client failed to retain any of their own records.