Bruin 350 4x4 Weird Noises?????

I have a 2005 350 Bruin 4x4 and was wondering about a noise I hear when I am heading down a steeper hill and put the rear brakes on. It sounds like a clunking noise and is kind of loud. It only does it if I am coming down a hill somewhat fast and then put on the rear brakes. The noise is coming from the motor area or trans not sure exactly. The tires are not locking up. The atv has engine braking and when it makes this noise the engine sounds like it slows down but I'm worried about the noise. Dealer told me it was prob normal but he didnt hear it happen
Any thoughts and suggestion will help!
Thanks
Craig

That noise is the clutch disengageing in the transmission letting the wheels freespin momentarily. try going down hill in 2wd using only the front brakes. if you start slowing down the rear wheels using the brakes the tranny lets you free-wheel. if you use the engine braking of the rear & the front brakes it will stop much quicker.

Thanks for the quick reply. Really appreciated. I will try that.
Thanks