When the lower steering gear housing is off is a good time to replace the oil seal on the steering shaft.
Below is a listing for it at TM Tractor Parts, you can look at the picture.
http://www.tmtractor.com/new/st/476fp.htm
Don't hammer directly on a new seal, it can dent the seal. Put flat metal on the seal to hammer on, or use a socket the right size, or a seal driver.
Be sure the seal lip is facing up. Put oil on the seal rubber and shaft when putting it together, so the seal has oil.
Be sure the shaft is clean and flat where the seal runs.
TM Tractor Parts has the gasket for between the halves also. The halves are supposed to have 1 dowel where the gasket is.
If the steering gear bushings are worn any, TM Tractor Parts has new bushings. Worn bushings make free play in the steering, it shows as the free play when turning the steering wheel.
The tie rod ends being loose make free play also.
Below is a picture from TM Tractor Parts showing where the seal is, it is the shiny part by the hole where the shaft goes.
For others reading this, the lower half has 5 bolts in a circle holding it to the upper half, I would check and tighten the bolts if you haven't lately. They can work loose from use. You can see the bolt holes in the picture below.