Moaning noise from left front at 35 and over
 

I have a 2000 Dakota 4.7 L 4x4 and have started hearing a low level moan when driving 35mph and over. I rotated tires and no change. I pulled the front wheel off and I can't hear any metal on metal sound from the hub when turning. I did check the axle and found the oil was gray, so I pulled the cover, rinsed the gears with WD40 and replaced the gear oil, but no change.
Can the hub bearings be replaced or do I have to replace the entire hub?

Replace the hub. It's not really intended to be rebuilt.

His truck is 4wd, a totally different system. The hub isn't rebuildable, I think, and not greasable. Just replace it if it's grumbly.

Sorry, missed that part. Here is a Ram 4x4. Should be similar.

The right hub has a bearing pressed into it. The left hub has a bearing pushed into it.
Two totally different processes.
Lol.

I found that same youtube video and replaced the hub last night. The bearing was pretty dry. Thanks

Hub's are actually easy to replace really. Take the wheel off, brake assembly off, axle nut off, and she'll slide right out. Certainly sounds like a wheel bearing issue to me.

Not on a 4x4. You have to unbolt the hub from the spindle. It can be pretty difficult to get off even after the bolts are removed due to corrosion.

Its still not a terrible thing. Corrosion or not.