Knocking from inside the dash?

I noticed  this knock eberytime I hit a bump, it seems to come from inside dash, center somehere. I checked the engime  mount its good , the transmission mount is tight. It feels and sounds like it is coming from the steering rack area. Us there a commom noise maker? Its a low pitch knock , like something big is lose. I can't  seem to find it

check rack mounts closely, they can crack