Growling sound 2400-2600rpm 105-115km/h

[PeterAllen]

Hi All .
On a recent trip I noticed a distinct growling sound on light acceleration at about 110km/h.
It sounds (albeit a lot softer) and feels similar to the noise the tyres make if you run along the beads that sometimes line the edge of a highway lane. You can feel it through the gas pedal (but not through the steering). Usually under gentle pressure on the gas pedal. If I push harder on accelerator is goes away and if I back off it goes away. Also noted that it seems to be effected by suspension as would change in sound when a bump in road was taken or at least slightly interrupting the noise.
Cant replicate it at lower speeds. Any ideas??
I have a collapsed vacuum pipe from drivers side rear rocker cover but don't think that would cause this growling.

[Keithy P38]

How long has it been since the big girl has copped some grease to her nipples?

[PeterAllen]

that and diff oils are I think the first step. I will also check all the bushes and engine mounts but I am pretty sure its in the front diff from the feel of it .

[Hoges]

Hi Peter,
All of the above plus
May be worth checking condition/ level of oil in transfer case ...
If from the description it's a type of 'resonance', I'd also check the handbrake cable adjustment and look for loose/broken (rubber) exhaust hanger mounts...
good luck!