Yes, but you do need the key in the ignition, it is only very old trucks that might bump start without the key. All modern diesels use electric control of the fuel solenoid valves and must have the ignition on to start. Bump start in second or third gear.
you are probly beter off trying to towstart it. do it in third. and be carefull that when it starts it doesn't rear end the towing vehicle!! ha ha i've seen it happen, v.funny.