Here are the install instructions that I got from Andy after a week of trying to get him on the phone.
As for what I have learned on my own:
Set the shock bracket just inside of the seam on the axle. Use old axle for orientation.
Line up the axle on the chassis using the rear holes.
Use a cut off wheel, dremel, or whatever you can to make the seat in the chassis big enough for the axle to fit in.
Make sure you attach shock absorbers before mounting axle.
Drill out appropriate hole location for the front mounting bolt to connect axle to chassis.
I also have found it much easier to work with these axles with the hubs and brakes off. I will clean the spindle and grease the assembly as I build from the inside out. They are rather heavy fully assembled, but I am also working solo.
Have a cold beer ready.