F15 chassis: differences between Cab 11/12 and Cab 13?

[Hanno Spoelstra]

Originally posted by Tony Smith
No Auxillary springs on this F15:

Nor on these:


But this one has:

Source: http://www.oldcmp.net/f15.html

I'm !
Only thing I can think of is that auxiliary springs were an option, but who/what decided they were to be fitted?

H.