I think you are reading it wrong. 3% of all Super Duties built could be F450s in 2024. That is Ford's prediction. Forecasting is very complicated for vehicle makers. They take the maximum number of vehicles the factory can build in perfect conditions and start subtracting from that based on
* estimates for employee turnover, sick days, no shows, etc.
* estimates for production line issues
* estimates for supplier side issues affecting all Super Duty models
* estimates for supplier side issues affecting all models and options (trim lines, packages, etc)
Combine that information with sales projections for each model and trim to determine what they can and should produce. They also need to calculate dealer allocations and then communicate all of this information to the dealerships to make it official. Undoubtedly some stuff will change and people will complain.
I am sure it is much more complicated than my simple description. I wouldn't want the job.