The ESOF (electric shift on the fly) trucks have the auto hubs. When you turn the knob to 4x4 the hubs should automatically engage (yes, they are vacuum actuated).
If you had the manual transfer case (with the lever on the floor) you would have manual hubs with the LOCK and FREE position.
My truck came with auto hubs...I've since swapped them out for Warn Premium Locking Hubs.
Yep, all 99+ 4x4s have unit bearing assemblies. Not the greatest design. Dynatrac offers the Free Spin kit that give you 35 spline outers, fixed spindles, wheel hubs, bearings, Warn Premiums, etc.. So that you can ditch the unit bearing setup and actually be able to repack your bearings. Also the bearings are spaced out better in the Dynatrac setup vs. the stock unit bearings. The stock unit bearings have both bearings fairly far inward (IMO).
Hope this helps.