Re: No 4WD
As it's a manual lever do you feel any resistance when moving it into 4wd? There should be a slight resistance before it slides into place. If it slides around freely, then the forks in the transfer case are shot and need to be replaced. If anything else it'd be a good idea to check out the fluid level.
If you have the electronic switch on the dash to change drive modes, then the TCCM or transfer case control module is shot. It does the switching for you (lazy mode), and your best calling around local salvage yards as a dealer part will be in the multi hundred dollar range. If you're familiar with vehicles you could change it out yourself. It's under the dash behind the center console (access through footwell area).
I'm not too familiar with the auto lock front hubs, but perhaps you should make sure they're engaged properly as well. The transfer case might be engaging fine but the front wheels could be disconnected....
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!