Here is what I can tell you about those axles. I own two Ford 7.3 diesels. One with a Dana 50 and one with a Dana 60 axle.
Say what you will they are actually great axles. Dana 50 is a bit weaker but unless you’re a caveman it will take a good amount of abuse before quitting.
the biggest things you need to do with those axles on maintenance to keep them running especially if/when running big tires.
cap off or remove and seal the vaccum port nipple on the spindle.
grease the unit hub bearings. I know they are unit hub and supposedly non serviceable. Simply pull the tire, brake caliper and rotor. Remove the ABS sensor and squirt grease down through the hole while rotating the unit hub. There is a company that makes a specific zero fitting that goes in there and it’s shaped like the ABS sensor. These are great if you don’t have front ABS you just got a service grease point.
I have frint ABS so I pop it off and personally use a bare zerk fitting on tip of my grease gun and I have a o-ring for a seal at the flange and hold it while pressing the trigger on the grease gun. You’ll feel the grease start filling cause the rotation if the hub will get some resistance, you don’t need to fill it all the way. Just a few squirts will do it. It works great. Then reinstall the ABS sensor.
every year pull the unit hub. On the back side of the unit hub there is a center bearing. Even though ford says it’s not serviceable it is. There are replacements available. Buy the CAGED needle bearing type not just the stacked needle bearing type. Pack it with grease like you would any other bearing. If this bearing gets left without servicing it eventually eats the half shaft by galling the machined surface. The axle shaft rides on that bearing. Replace the yellow orings at this time also.
the factory manual locks are also serviceable. You can get aftermarket hub locks. Mile Marker makes a nice cheap set that works well. Warn also makes a kit. Bit more expensive
If swapping ball joints get Dana Spicer. Don’t bother with any other brand. I’ve rebuilt six of these axles for myself and friends and the only time I had issues was with ball joints made by other brands. I had no say in the choice of materials as it was friends trucks. They however weren’t happy when 30/40k later they had to redo their ball joints.
as far as the unit hubs themselves Timken. Don’t bother with any other brand.
that axle was insanely cheap. Around my area they run 800/1000 bucks