Your local NAPA store can also order Cub Cadet parts.
After the steering gear, the axle pivot is the biggest source of play in the steering. Consider HD "Heim" joints for the tie rod ends, available from McMaster Carr. Be sure to check to see if any of the joints are "reverse" or left-hand thread. Finally, for your 123, be sure you have the pin that holds the "Steering Arm Ass'y" on tight and that you are able to turn the wheels "lock-to-lock." Some people resort to a "trick" of moving the hole on the steering arm a little inboard to accomplish this.
The key to keeping the steering trouble-free is keeping the grease to it. For instance, the recommended lubrication schedule for the front pivot pin is every 10 hours of service, not every 35 years to which many are subject.
