Didnt they make king pins bfore 1937.?

I am about to order my axle and looked at the Speedway catalog.Now they list an axle 1928 to 1936 Ford..( Super Bell...) I beam.Now when I popped over to order a kingpin set they say they only have sets that are made for 1937 to 1941 OR from 1942 to 1948,UH..how can they sell an axle you cant get king pins for or am I reading this wrong somehow..?

 

I'm using a 32 Ford heavy axle with 46-48 spindles using 42-48 kingpins. In 1937, Ford made the change to using a thrust bearing under the axle eye. This makes the spacing between the spindle bushing bosses wider apart as compared to the previous design, Model A thru 1936 era spindles. Kingpin diameter is the same thru all of these applications.

 

They are assuming your using latter spindles or there replacement ones. 37 was the first year for the thrust bearing under the Pin boss. Pre 37 was above the spindle below the Head of the King Pin. Look at a stock Model A and you'll understand. They are just targeting the most Common used parts. The actual Pin Boss is the same Model A up. Only the spindle changed along with the actual King Pins. If you look close you see stock A pins and spindles and it's getting late Hyd brakes. Thrust bearing is just below the round Knob and above the Spindle. I know it's hard to see in all black.
The Wizzard

 

You need kingpins to match your spindles.