I was told that much of the slop in my steering was caused by a craked pin or shaft inside my power steering box, and that until that was fixed the car is unsafe to drive (because that crack may shear completely resulting in the loss of steering).

Is this a common ailment of older steering boxes, such that I shouldn't be looking for a junkyard replacement...etc?

I see replacement boxes available via google for $285/ea, before I place the order I wanted to check for all the 'common knowledge' about these boxes that I'm not up to speed on been away from the car for too long.