I need the rod under the tractor that hooks on to the steering wheel and then end hooks to the left wheel, the end that hooks to the left wheel the ball joint fell out and is worn

Hi,
Need model number (under the seat) to verify the correct part, but the end is usually replaceable (theaded) and the two most common are part #723-3018 (3/8-24 thread) and 923-0448A (7/16-20 thread.) It is not a hard and fast rule, but mostly the first fastens thruough from the top and the second from the bottom. The first part of the thread sizes is the fractional inch measurement (3/8' and 7/16') and the number after the hyphen is the threads per inch (24 and 20.)
Peace,
Clarke