A couple of issues to fully explain. The SD7 / SD9 had more detail variations that the E8/E9 and it was the first locomotive for the new factory and the new team. Two distinct models and a lot of road names.
There are only 16 road names for the SD40-2 and it is likely some won't move forward based on reservations. Furthermore, the factory is up to speed and doing great work as evidenced by other projects they have released.
The E8/E9 Amtrak run had some interchangeable details, but that was limited to the dynamic brake and the snow shields over the winterization hatches on the former UP units. The reason for that was someone personally guaranteed the Amtrak run with their own funds as far as I understand otherwise it was going to be canceled. I fully expected them all to be based on UP models, but the investor had some of their own input into the project.
