Yes they are numbered. I'm only guessing, but I attributed no one wanting to touch mine to the dealer, who can't bolt on a splitter, installing it's new motor.
Long story, short, I went to 2 dealers until I found one that sounded like they knew what they were talking about.
we had to do the Oil Consumption test over again, the Tech send all the finding and pictures to Ford360
and he said we should hear back in a day or two, it took a total of 12 minuets to get the approval and one week
to get the Motor shipped and installed.
Ford Shipped a 2019 GT350R Motor (Build Date 12/12/18) so hoping all the latest parts are in it.
the only thing they had to change was the Oil Pressure Sensor connector, the 2017 GT350 plug
would not fit, so they might have changed the sensor for the 2019's I heard there was some leaking
a while back.