Transfer box or transmission not engaging

[jfalcon]

Was at a stoplight on a hill. Once the light changed, made my turn then heard a clatter then suddenly no power was being sent to the wheels. Pulled off the side of the road (still on a hill). Shutdown, restarted then tried to engage in any gear. Had the obdIi cable plugged in so went into protools and looked for errors which there weren't any. Reset the ECU of the transmission, no difference, reset the ECU of the x drive and it would engage for a second then disengage then engage again then disengage then engage them disengage.

Any idea what it could be?