There is no outer axle seals. Nothing stops crud from entering the axle tubes. MAD 4WD does make some D60 outer seals. These will probably fit with the Superduty adapters but you may want to chat with MAD about the compatibility with the AAM 9.25. The jury is out on how much they really help. I run them on my Jeep but don't do any kind of deep mud bogging on a constant basis. A lot of the mud guys say they trap crud and won't let it out once it gets in. The problem with the outer sealer is that they have to stretch side to side quite a bit to allow for the natural movement of the inner shafts when the knuckles cycle through a turn. I would not recommend the outer seals for your application.

As for lubing the spindle bearings, I would highly recommend removing the spindles to do so. It is the only way to physically properly "pack" the bearings. Grease will not properly penetrate the rollers any other way. They aren't any different that a wheel bearing in that regard - grease has to be physically pushed into the bearings.

I should also add that I was under the impression that the slop with axle shafts you were referring to was with the spindle removed from the knuckle. It now occured to me that you meant there is slop with the entire front end assembled. As comp-ignition mentioned, the spindle bearing in conjunction with the locking hub support both ends of the stub shaft. The stub shaft in turn supports the outer end of the inner axle at the u-joint. The inner portion of the inner shaft is supported by the carrier. If you have play at the stub shaft and your u-joints are tight, your spindle bearings could be fragged. I apologize for the confusion here.