Here I have both an 8 and 12 cylinder front axle side by side for comparison
8 cylinder axle beam is 1 3/4" wide
8 cylinder axle has this notch near bolt holes
8 cylinder spindle is smaller, .750 and 1.312 are the bearing surface diameters.
12 cylinder axle beam is 2" wide
12 cylinder axle is wider in this area
12 cylinder spindle is larger. 1.00 and 1.50 bearing surface diameters.
8 cylinder stamped "A 30118" from a 1931 car
It appears as if the steering arms are the same for both 8 and 12 cars, the leaf spring U bolts are the same also. I will pull these apart and photograph their respective part numbers. (10.27.14)