[Heathejj97]

Ok so this noise is getting to me and I'm scared something's going to blow at the worst time, btw sorry for the long description.
So i bought the car recently on 235/75/15 maxxis bighorn muddies, car is fully stock other then the 2" lift with extended shackles, gearing isn't the best as its stock but it mannages alright.

The noises are: as I'm driving at any speed under full acceleration and when costing i get a grrrrrrr sort of growling sound. If i apply a tiny bit of throttle so its not quite costing it will stop, but come a back as i accelerate more.

Also there's a whine over 90kph in 2wd and a whine in 4lo when i reach around 3rd gear in the beach

I have removed the tailshaft and locked hubs and driven it in 4hi as a front wheel drive and the problem is 60% quieter so i assumed the diffs worn too, i then swapped the transfer cases to one that never made any obvious noise from my other sierra, and reconnected the tailshaft- the car was almost perfect and there was no whine at 90 or over, tho thee was a bit of noise still while accelerating etc.

After a 150km beach run like this the sound is worse then ever before

I guess this must mean its a diff issue? I'm really lost and cant seem to pick out the issue-

Thanks a heap! josh

[MrRocky]

Rear diff i reckon
Change sidegears over and swap front and rear diffs

[watermouse]

Also could be worn wheel bearings as they can change sound with power on and off but I think MrRocky is right.

[Heathejj97]

Ahh ok thanks! And I really don't know a lot about diffs, I can rebuild an engine but I have a fear of diffs, I'll see if I can get a cheap complete diff

[Heathejj97]

Also if I walk it in 4th at 50kph (borderline engine lugging) there's a very loud growl- like veryyyyyy loud and the car vibrates too