Okay have a 99 Ford Ranger 4 x 4. When I get to about 60 I get a pretty good humming noise coming from the front. I've had a couple of different sets of tires on it but it doesn't make much difference. I can't find anything obviously wrong with it. I could use some input here. Surely someone else has had this problem?

 

Welcome to the forum

Not a common issue or would be more posts about it

1998 to 2000 Rangers use PVH(pulse vacuum hubs) but people often changed these to Manual hubs.
Do you still have the PVH hubs and do they work?

Humming wasn't an issue with these, not locking in 4WD was, lol.

1998 and up 4WD Rangers also got new front drive train, 1997 and older were different

There are CV joints instead of u-joints on the front axles.

With hubs unlocked the front axle and drive shaft should NOT be turning in 2WD, have you checked this?

Just roll truck forward or backward while someone looks front drive shaft, it shouldn't move

If it does then hum could be coming from axles, differential or transfer case
If it doesn't then front wheel bearings would be best guess