Try this. Jack the front wheels off of the ground and disconnect both lines. Then try to move the wheels by hand. They should move and fluid should spit out of each side as you move the cylinder. IF they do, all is OK at the front end.
IF they won't move, disconnect the cylinder at one end or the other and try again. They should move fairly easily. If not, problem with axle pivots or tie rod.
If everything is OK at the front end, that leaves only the steering gear box.
I have never messed with the insides of one, but my guess is that with the lines disconnected (probably need all 4 off) the steering wheel should turn pretty easily.
I know that with my 284 when the wheels are off the ground, I can turn the steering wheel and move the wheels lock to lock, even with the engine off.
Gear boxes should be available at most dealers.
Hopefully someone will post actual gearbox troubleshooting.
Thank you, I'll try some of this taday