Can you share an example of your text file? You may edit any sensitive data out and replace with random data. Does the file need to be changed in anyway, or are you just changing the extension of the file? If it is the latter, then you can just use the FileUtils to rename the file. If it needs to be changed, then you'll likely want to use a C# script to alter the contents. I don't think performing a SaveAs using the Excel Connector would actually convert the file.