low50's, John Deere tractor dealers have the exact correct grease for steering gears called "Corn Head" grease. It is very free flowing and keeps the bearings/bushings well lubed. GM used to have it also but it's discontinued now because everything is rack and pinion. Chassis or wheel bearing greases are wrong for a steering box.
You can get the bearing you need from any bearing/power transmission supplier. All they need to match it is a number or its physical dimensions.
