Actually the 48 to 50 supports have two small holes in the upper left hand side front ( just under where the sheet metal air deflector passes through the upper bolt) to mount the 48 to 50 horn and bracket. Those two little holes were eliminated in 51 when the horn or horns (hi and lo on the deluxe cab) were mounted on the hood.
Otherwise same/same 48 to 52 F1 to F6 conventional cab.