First off....relax. The shafts are shorter for production reasons, nothing else. This is not uncommon. Superior/Foote does the same thing. I wondered about this when I got my new set of evolutions from Superior, but Chad looked it up and it was done that way on purpose. I forget the exact measurement so can't remember it off the top of my head, but if you have at least x amount of inches contacting the side gears in the carrier then you're fine. When you pull your stock axles out, you'll notice that the end of the splines do not have signs of wear on them, because they were never inserted into the side gear. Of course this is a moot point with shorter axles since the unit bearing pulls it out of the carrier a bit when the unit bearing is bolted to the outer C. Thus, the location of the ears and u-joint is in exactly the same location. The only difference is that...1. you don't have extra unused splines on the axle, and 2. the axle isn't pressed all the way into the side gear. It's perfectly fine that way and does not lessen the strength of the axle or the side gear.
Second....Alloy USA is now Ten Factory/Motive Gear. Notice the Super D44 kits with 30-spline outer axles ;-) They are just as strong as all the other axles from all the other middle men....er, I mean "manufacturers", with maybe the exception of Yukon (since those actually are different axles). Which brings me to my third & final point...
All the axles from Superior (with the exception of the Evolution series axles), Alloy USA/Ten Factory/Motive Gear (G2 axles are actually Ten Factory axles repackaged & relabeled BTW), and Yukon axles.....are made in India, not China. They all come the same place and go to different "manufacturers"...if you can really call them that. Really, these companies in the US selling these axles are the middle man/quality control dept. Ten Factory actually has a QA facility and department to check that their axles meet their standards, but they do not actually MAKE axles. Some are imported from India, the others are made by a US company called Foote. I'm not sure if Foote is now owned/partnered with Superior now, but that is who actually MAKES American-made axles. One of the axle guys from Superior left to start his own axle company a while ago and is now in charge at Ten Factory. If you compare the Ten Factory axles to Superior axles, they are EXACTLY the same because they came from the same place....with the exception of the Evolution series from Superior. Those are different and you'll know if you have one because "USA" will be stamped into the ears...and you'll pay for it too! I have broken TONS of axles/ ring gears/lockers/spider gears/etc, but I have yet to break.....I'm better not say it
The Yukon axles are noticeably different when you compare them to the Superior or Ten Factory imports, but they still come from India too.
Good luck with 4 Wheel Putts, especially when it comes to gears. While setting the pinion depth, backlash, and shims is not brain surgery it still takes some experience and a little patience to get it right. Whoever is setting up your gears, make sure they know what they're doing.