The Upper and Lower Ball Joints on these axles are at different angles, in other words the vertical axis of  the Upper and Lower Ball Joints are neither inline or parallel to each other.   To compensate for the different arc of each Ball Joint during turns, the modest sized, straight shank, 7/8" diameter stud of the Upper Ball Joint is vertically free-floating in a 1" long sleeve.   Consequently, the Upper Ball Joint does not support any weight, it merely keeps the knuckle in place.  On the AAM axle, the upper Ball Joint is not really a Ball Joint at all, instead it is a floating King Pin that is about the same diameter as the King Pins found on 1966-1981 Ford F100 4x2 1/2 ton trucks and light 3/4 ton trucks with GVW's of 4,700 lbs-6,900 lbs..

The Lower Ball Joint is load bearing, in fact, the two Lower Ball Joints carry 100% of the front axle weight on your 2003 or newer Dodge Ram truck.  Dimensionally, the outside diameter of the Lower Ball Joint is only 4% larger than the Ball Joints used on 1972-1986 Jeep CJ's (and other light-duty models of that era) which has somewhere between 1/4 and 1/3 of the front axle weight of the Dodge Ram, plus both the Upper and Lower Ball Joints on the CJ are load bearing.  In addition, the Ball Joints used on older models like the Jeep CJ and 1994-1999 Dodge Ram 2500 and 3500*  shared the same vertical centerline axis and were pre-loaded to compensate for wear.   With the AAM front axle steering geometry using differing Ball Joint angles, no preload is possible, therefore, any wear means loose Ball Joints. 

Yes, lack of  lubrication with the non-greaseable factory AAM Ball Joints can be a factor, however very few of the failed Ball Joints we cut apart are suffering from a lack of lubrication.  Replacement Ball Joints in both greaseable and non-greaseable versions are available from quad4x4.com, plus there is even an offset upper Ball Joint out there (which in my experience is both short-lived and of limited use).  Installing Greaseable Ball Joints and regularly greasing them may provide longer service life under wet conditions, but with the AAM axle, chances are you will need to replace the Ball Joints on your 2003-up Ram 2500 or Ram 3500 4x4 truck every two to three years.  One would not mind the short Ball Joint life so much if these trucks steered better than previous models, were not subject to "Death Wobble", or had longer tire life.

I found it very interesting that the 2003 Dodge Ram Truck Service Manual does NOT give any specifications for allowable Ball Joint movement or looseness, yet later manuals allow for up to an amazing 0.090"  of vertical movement and 0.060" of horizontal play.  You can interpret this information any way you want, but my experience has been that anything more than a fraction of the amount of play Dodge says is permissible will adversely affect steering and tire wear on the AAM 925 axle.  (Note: 1/16" = 0.0625")

*1994-1999 Dodge Ram trucks with the Dana 60 Front Axle have Lower Ball Joints that are nearly 10% larger than the AAM axle.  Average Ball Joint life for 1994-1999 trucks is close to 150,000 miles or 7 to 10 years.  All 4 Ball Joints for those years carry weight and are pre-loaded to compensate for wear and dampen steering shocks.