I was having much the same problem you were Rick. A lot of vibration at low speed. It would disappear at higher speed. I thought it was the transmission. Finally, the pinion nut fell on the road. Along with the pinion flange and back of the driveshaft and seal. I put it back together right on the lonely dirt road and it ran nice and smooth all the way home. I was lucky, this can be a deadly thing when this happens.
