How is your front drive shaft? Check all the joints for play, you could even take it out and go for a ride and if the noise is still there obviously not the problem, there are only 8 8mm bolts that hold it in.
If it's only when applying power it might be in the diff. I'd wiggle the pinion (input) shaft and see if there's any slop. Usually this is accompanied by a leak because the loose pinion shaft messes up the seal. If it's the carrier bearings you'll have to pull the cover to investigate. Hub bearings are a common failure too but from my experience, they'll make noise at speed regardless of whether you're giving it power or not.
Sorry lol. It'll be obvious when you pull the cover off. You'll see the teeth running perpendicular to the ground. Grab hold of it and try wiggling left to right. You may have to do it with the front wheels off the ground and in neutral so that the rest of the drive line isn't bound up keeping it tighter than it may really be. Here's a pic of mine, you can see the large teeth sticking out, that is the ring gear. Inside the cover, you see to the far left and far right the bolt heads? Those are holding in the carrier bearings on each side.
I was going to try removing the shaft but then it only does it when im on the throttle. So can't see it making a noise without the shaft anyway.
Just being out to check the shaft and its got no play. Feels solid.
Not true I had a bad front shaft that would make noise on acceleration sounded like a train or a bad up hill climbing roller coaster and would be quiet on deceleration. If you don't find anything in the diff try removing the shaft its not going to waste any time giving it a shot