I installed warn manual hubs a while back,truck had the black auto hubs with the select auto or lock,drivers side was dry on inside no lube at all,pass side ok,now a few times a noise almost sounds like a wheel bearing last maybe 10 seconds (Drivers Side),
Those Superduty unit bearings have plastic parts in them (I think they might be the bearing races, but not sure) and can fail suddenly and spectacularly. Get the front end looked at ASAP. If you intend to keep the truck for a while, you might consider replacing the unit bearings with a real spindle-and-hub system; Dynatrac has one
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