Supposed to be in 3 locations on top of left rail. Lots of threads on here about it. Not all fords outside of USA had a serial number stamped on them.
Those are some of the best examples of frame numbers I've ever seen, seems the majority are hit & miss as if the worker had to run along the moving assembly line & try stamping the best he could.
maybe the guy stamping it got distracted. I doubt that the production line stopped if they got a bit behind. .
Also, 1932 Ford Commercial Cars, i.e. the Pickup, Station Wagon and I think unbodied drive away chassis’ sold to body builders only had a serial number by the firewall leg.