I see the little plastic cap that are on the ends of my axle tubes...and I helped put some Alloy USA axle seals on my buddies rubicon....are these things required when you headed into water? does anything make it past there and into the pumpkin that I should worry about?

Also, now that I have axle sleeves...I probably cant put seals in now...right?

 

They do more damage than good, IMO. First off, if anything get past them (water, dust, mud, etc) it's going to stay. Second, if you spring an inner axle seal leak, you likely won't notice until you lose the majority of the fluid in the dif, if at all. You won't notice the leak till you may have already done damage to the bearings.