"Of course there is a lot of leeway in these axles so it probably won't matter much either way."
Yes Bob, These axles could be taken apart and repaired in the middle of nowhere with a hammer Rock and a screw driver, and maybee a set of vise grips, in a mud puddle,
Filled with just about anything that resembles a lubricant and get you where you need to go,
They also can be carefully cleaned and set up with new components , knuckle housings centered, pre load set, �filled with a correct lubricant, and get you where you need to go for 30 plus years without ever messing with it,
The question is how much improvement is there going to be when you center the knuckle housing over the factory method....will it be noticeable, all other things equal? After all ...when you turn the wheels, the knuckle is no longer aligned perfectly and the joint takes care of it. What is .010 misalignment up and down compared to the misalignment from driving around a corner? Preload is important, yes.
We all want our jeeps to last. Sometimes we have different methods. Sometimes we agree with the book, other times a better way has been found over the years. In any case, we are aiming for the same goal,keeping these fun little beasts running for another day in the woods. Life is too short to waste on name calling, endless arguing, and constant harangueing over pet peeves. If it keeps up I will have to put on my moderator hat, and ya don't want that, do ya?? 
No need for the mod hat,
I will be good, Now your turning the wheel taking things out of alignment, No the axle is still straight, and yes the joint allows it to transfer power @ a angle, but is still straight
These U joints and cv joints can handle one load, only, and one angle,
In my process of researching this subject I read up on "Thompson Couplings" these could handle both, axial and lateral,
With only one joint in the shaft like these axles only one angle , (steering), if you had 2 joints in the power transfer shaft, then okay, �I discovered this trying to run a hydralic pump off only one u joint, could not make the shaft true enough , needed 2
Also Bill,
"The question is how much improvement is there going to be when you center the knuckle housing over the factory method.."
What I am trying to point out is that what is written in the book is not the factory method, not @ all, There is no way that Old Man Willies would have had Rosie the Riveter fiddling around with taking shims on and off, dialing in the knuckle,
Waste of time, Some sort of tool or fixture installed in the housing, lower gap measured and proper selective shim installed,
Also simply installing all the thickness of shims and then taking them out to set pre load, only and no thought to centering, No I really dont think so,
What really sells if for me is years later the world renowned Japanese machinists, centered up this axle housing very much the same way with selective shims, a very critical aspect in the replicated axle because of the location of the axle seal, off just a fuzz there and the seal leaks,
These shims take up machining irregularitys, By following the book word for word, basically states that Old man Willys had the knuckle perfectly centered something the Japanese could not do some 10 years later,
Maybee,
Preload is important, yes.
"Also, in case the main purpose is to prevent false
brinelling, the exact amount of preload needs be
calculated just enough to prohibit the creation of
clearance by vibration load, so as to prevent rolling
element from being vibrated by outside vibration
when shaft is not rotating."
And Yes bearing preloading is a rather exacting, in my humble opinion the ranges given in the books are rather broad, not exacting @ all,
