My 02 Explorer XLT 4.0 4x4 has two things going on...........

1-The rear axle grinds and vibrates on left and right turns when starting from a stop. It doesn't happen until I've been driving for a few miles. I'm fearing a differential rebuild, any thoughts?

2-The other night, from a dead straight stop, the transmission(or rearend) seemed to be skipping, it wasn't a smooth soft slip, it was more of a jerk, that's why I thought it was related to the rear diff. HOWEVER, right after that, the O/D off light flashed rapidly, and it would not enter O/D even if I turned the switch on and off. Other searches I've done are telling me that the flashing light is a sign of a dying transmission. Any thoughts?