The difference between them is on the passenger side. They don't have a disconnect mechanism like the part time models do. Basically it's a dog clutch and a shift mechanism that slides the collar to engage or disengage the passenger side from the diff. So when in 2hi the drivers side shaft spins at full road speed. (Roughly 6-800 RPMs). And the shaft freewheels inside the diff that's not spinning. So that drivers side shaft spins in the needle bearing at high speed. But the bearing isn't actually in the housing. It's in the carrier. So if the diff is spinning the bearing ends up being stationary relative to the axle stub shaft and the carrier. I think the limited has the bearing, but it basically never goes bad.

On the passenger side they use a similar bearing on both the limited and the rest of the models. And it is fixed in the housing so it always spins on all models. But that one is a big roller bearing. It's similar to a wheel bearing on a small car. It's way overkill. And rarely ever wears out. I've never heard of one going bad.

Hope that kinda helps. No problem being new. Everyone was once. It's really hard to explain this without seeing one torn apart so maybe my explanation doesn't make sense anyway.