2004 Ford Ranger Squeal in rear of 2004 Ford Ranger

Recently began to experience squealing noise that seems to be coming from the rear of my '04 Ranger. Noise begins around 25mph and continues up through about 45mph, not sure if it simply quits from there or if the noise has gotten to the point that it is so high picthed/rapid that it is beyond my hearing. Noise is present no matter which gear vehicle is in at that speed (manual trans), it also continues even if out of gear and in neutral until I coast to below about 25mph. Was thinking the problem may be the universal joint but I am not certain. Drive shaft does not seem to have any play in it and I haven't noted any vibration yet so not sure what to make of it. Appears somewhat blackened around the joint but otherwise seems okay. Was also thinking possibly wheel bearing? Any help isolating or narrowing the problem down is welcome, if you need further information ask and I can provide.

Thanks

-Josh