winning noise when i go in reverse noise is in the back on 1994 Dodge Dakota

when it is cold especially I crank up put the truck in reverse and the back area makes a loud wining noise. It makes the noise when going in reverse only. it does it most of the time, but always when its cold. I just had the transmission rebuilt less than two years ago. I don't think it is that. Could it be the pinoin nut on the rear axl

Asked by for the 1994 Dodge Dakota
Great! your truck is making a WINNING noise, much better than a losing noise...right?