Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
If you are hearing this noise from the front of the vehicle your most likely suspects are going to be the tires first, followed by the front wheel bearings. These are both very common failure points and common complaints.What I would be doing at this point would be to get the truck in the air with a helper "driving" it to ~40kmh in 4H and listening underneath with a stethoscope. This will confirm the location without fail.If there is no noise while doing this, then you know the tires are going to be at fault, as the lack of contact on the road results in silence.If the wheel bearings are at fault, listening at the back side of the spindle(s) right near where the axle shaft goes through should produce a very noticeable rumble.Of course if nothing is heard there, then the rest of the vehicle can be probed with the stethoscope to help isolate the origin (front diff, for example). Given the narrow range of speed that the noise occurs it is of course possible that there is a wear issue on the planetary set inside the transmission.... however this will usually be heard either central or all over rather than just in the front end; likewise if you are free wheeling in neutral the noise would silence if this were the case. Never the less, the stethoscope again would help identify this if you found that the noise seemed to originate roughly in the middle of the transmission.