whinny noise when braking?

[imryannn]

Most of the time it happens when I am braking, and when I am about to come to a complete stop it makes a clicking noise (Like the sound you get when you click into 4wd) and then whinny noise stops. While the noise is happening the tcase shifter has a lot of vibration...
any ideas what this could be, because its starting to get irritating...

thanks in advance