I'd be surprised if the axles vary from one unit to another. That said, once you custom order an
axle, you own it.
I also noted when I was measuring mine that the distance from the outside of the frame to the inside of the wheel lip is very tight.
UHaul used a deeply offset wheel to get around this. If you plan to use a zero offset wheel, make sure that you account for this difference in offset.
I did not replace my
axle, but instead am in the process of machining hub adapters to take me from the 4 bolt
UHaul / Camaro hub to a standard spindle so that I can add
brakes.