I was a Jeep junkie for a while from a 60's wille wagon and a hand full of CJ5's in the mix, few Nissan and toyotas in there as well... never owned a "automatic hub" system. 28yrs Mechanic I have replaced more trashed auto hubs than manuel ones.... mostly to not being serviced due to the owner, I haven't had any wierd issues with hubs locked in and driving in 2wd in short distances... maybe a driveline vibration? but not this growl/squeal ordeal... Like I said this 94 tracker has 4xx,xxxmi on the clock, who knows what might be missing in parts or changed? It didn't make the noise before with the old trashed CV axles (half shafts) and it does with the new Rock Auto replacements... but alas, bearings were changed, drive lines got new U Joints (front and rear) rear pinion needs rebuild but still somewhat "driveable". Engine was rebuilt right after I aquired it. 16v block/8V head..lol so who knows I guess...