Power steering noise

[dremmick]

I have a power steering gear box and pump from a 1978 installed on my 67C10. The problem is when I turn the wheel all the way to the point the rim stops turning, but oddly I can still move the steering wheel some more, and it starts to squeal loud!! It only squeals like this once the rim stops moving. I find it weird I can rotate the steering wheel some even after the rim stops turning. It there something that should stop the steering wheel from turning this far? I did change the pump today and it still does the same thing. Sorry about the view of the video. It's taken from the back side. If you look closely you can actually see the reservoir and pulley move with the sound.

Here is the link http://youtu.be/QS8rNI2ks70