Also reference parts book, these pages
http://chevy.oldcarmanualproject.com/parts/1929_54/379.htmhttp://chevy.oldcarmanualproject.com/parts/1929_54/380.htmThe 1 ton axle beam and spindles I believe are very same parts as 1.5 ton standard front axle (excluding heavy duty axle option).
They have the same front spring width at 2" and will physically interchange.
The 3/4 ton has 1-3/4" springs, so even though the 3/4 ton axle beam is the same forging as the 1 ton and 1.5 ton it is not interchangeable, it is drilled for different springs (u-bolt width).
Curious about 2 ton? Different axle altogether, but the axles will bolt in or swap from 1 ton through 2 ton if you try. Again all have 2" springs. They're just not the same axles as far as brakes, spindles, wheels, and such.