You don't need one....but your cooling system is basically worthless now. I would look into either A) replacing the fan shroud or B) installing electric fans. Your mechanical fan is better than most electric fan setups so i would suggest replacing the fan shroud.
You could probably squeak by without a fan shroud for some time if this is your daily, but I would keep an eye on your temp gauge and avoid sitting still and idling. Your only real form of cooling is your heater core fan and any wind passing through the radiator fins when you're moving.
You're new around here, but next time post these type of small questions in this thread:
http://zilvia.net/f/showthread.php?t=297481