Is this the spindle you are refering to?
Steering Motor Spindle
They are not terribly difficult to replace. If narrow front, rollomatic front end needs to be removed. Jack up front of tractor and block up. Remove 4 bolts attaching rollomatic to steering spindle (1 1/8" wrench). If wide front, Remove front axle bt removing steering arm from steering motor spindle again 1 1/8" wrench. Then remove two bolts and 2 nuts holding front axle to frame. support axle and jack up tractor off of the front axle. roll axle out from under tractor. Then turn steering wheel full right or left. there are timing marks on spindle and spindle retaining plate. make sure timing marks are aligned. Remove 6 bolts holding retaining plate on. Leave 2 bolts in by a couple of threads to keep spindle from falling out before ready. Then retaining plate normally needs to be pryed off of the 2 large dowel pins.Once it is free from dowel pins finish removing bolts and lower from motor. Place spindle assembly on bench and remove snap ring holding on bearing. Bearing usually will slip off of spindle. Then retainer and seal will lift off of spindle. When reassembling, be sure to use new seal, inspect bearings and replace if required. Align timing marks the same as when removed and reinstall spindle assembly. I usually use new bolts. Original bolts were often grade 2 soft bolts. Replace with 6 grade 5 or grade 8 bolts and tor, ue to 85 ft lbs. If using new bolts for rollomatic or steering arm, be sure to use correct length bolts. Bolts too long here will ruin seal on spindle and can damage spindle retaining plate. These 4 bolts should be 3/4" x 2 1/8". 2 1/4" length is too long, also be sure to use lock washers for proper thread depth engagement.