Hi, Well i am a little confused about the result of disconnecting one half shaft. try this, with the axle half shafts connected, disconnect the drive shaft at the front of the diff. now try to roll the car. if it does roll watch the front of the diff to see if the input flange turns. i doubt that the car will roll.if the flange does turn then the diff is possibly good. if it does not turn push the car backwards and try to unlock the diff. if it does free up it is still bad. changing the diff is long but easy. i think the gear inside the diff has seperated from its carrier. next check to see that the drive shaft rotates easily. if not then the trans is the problem. least likely is that one axle half shaft has gone bad. good luck. e-mail me with the results i am puzzled about this one. thanks for a tough one! stone stone racing co phila pa 215.592.0265