Through the years, I have asked regarding the "hash" marks. They are the same and seem to have nothing to do with being automatic or manual. They are the same regardless of engine or rear gears.
I asked a retired Ford engineer and he did not know why and guessed it might have to do with calibration?
In my truck is [was?] a NOS F600/800 medium duty speedometer which goes to 999,999.9. It is a replacement [service] unit designated by having red colored digits for the tenths. It, too, has the marks.
The metric versions, which go to 999,999.9 kilometers, do not have the hash marks.
The speedometers with resettable trip meters do not have the 35/41 marks, due to having the odometer set higher to make space at the bottom for the trip meter.
I have attempted to see a pattern, unsuccessfully, in comparing the standard and metric [roughly]:
10/15 MPH = 16/24 KPH
35/41 MPH = 56/66 KPH
67/78 MPH = 107/125 KPH