Steering box question

I found a good deal on one that came off a car sitting in storage for 20 years. The box was new when the car entered storage. I just don't know if 20 years of sitting is a good thing. I only want to change this thing once. I can turn it by hand and it has no play,but that is not the same as under a load installed in a car. My alternative was to have mine rebuilt by one of the vendors that many on this form use.