Link/Source: http://boeing-test-flights.blogspot.com/2017/01/blog-changes-regarding-boeing-changes.html

Sunday, 8 January 2017 Blog Changes regarding Boeing changes to Customer Codes

Boeing will no longer use customer codes on the 737, 747, 767, 777 lines bringing them in alignment with the 737Max & 787 lines. These changes have already been made on the FAA Certificates. The changes are effective with the following Line numbers for each respective Production Line.

So we have made changes to entries to reflect this change. The chart below shows how the changes impact the Model for each Production Line: