Essentially your orig 229 has been swapped out with an 80-82 219. Common swap. The front axle shaft is engaged via the vacuum system. When you switch the dash vac switch from 2WD to 4WD it first routes the vac to and engages the front axle first and then engages the tcase. With the vac axle you must come to a complete stop before shifting or loud ugly crunchy noises come from the axle shaft. It's a splined 2 pc shaft that is connected/disconnected via a splined collar so the shaft can not be spinning. 83 and 84 with the 229 and vac axle have the pull down shift-lock knob on the dash 2WD/4WD switch. The knob makes switching the switch a 2 handed operation insuring you are stopped and not trying to shift on the fly or BOOM. With the swapped in 219 you no longer need the vac system for tcase shifting(no 2WD mode) but you DO need it for the axle shifting. The useless unlocking hubs installed only lock/unlock/disconnect the wheel to the axle. Have nothing to do with engaging/disengaging the splined 2 pc axle shaft via the collar. The hubs just provide a false sense of security.
Some folks with the 83/4 vac axle have done work-arounds locking the axle shafts together permanently but I'm not familiar with those mods. The orig vac system should work fine if maintained. I'd highly suggest you get a copy of the 83 TSM to study how it all works. The 83 TSM isn't a full shop manual for 83 but rather just a supplement to the 82 TSM covering the changes for 83. It'll explain the 229, vac system and vac axle with diagrams.
If you don't want to hunt down an buy the 82/83 books you might find them online at http://oljeep.com/index.html