It's my understanding that the axle forging is the same for the AD 3/4 and 1 ton and light duty 1.5 ton.
True the spring width is different (1.375" for 3/4 ton) and therefore the u-bolt holes are drilled differently in the axle pads. I believe when new they used a different dab of paint color to indicate the difference between these otherwise identical, including forging/part number, axles.
Spindles I think are the same for 3/4, 1, and light 1.5 ton.
Back to the original question. If you're handy with a rat tail file you could slot each u-bolt hole 1/8" wider and use the 3/4 ton axle and spindles in the 1 ton. I have not done so, but fully believe it is possible. I have used 3/4 ton hubs (only) on a 1 ton axle/spindle, no issues.
