Contact the folks at Danhard, Inc., 214-328-8541 or www.danhard.com
. The condenser is a model #00864, they'll know the exact fan you need for it. Good people to deal with. You can also see if SMB stocks a replacement fan.
FYI, it is not uncommon for pebbles to work their way into the fan shroud and cause the motor to "lock-up", use a water hose to clean it out. Also, the ground wire on the lower condenser fan is known to have corrosion issues, so make sure you double check it while you're in the area.