I am looking for info on a rack system for 51 chev with stright axel if you have one or know where I can find one and which is the best that you know.
Frame mounted racks do NOT work well with straight axles !! And axle mounted ones need a slip joint in the steering shaft and don't work real good either. Re think this.
In my professional opinion, these cannot be made to work properly together. What does work, is the Toyota 4x4 power steering conversion, if you can stomach some furrin parts on your Chevy.
These guys make r&p steering for straight axle cars (and others) might give them a call. http://www.unisteer.com/
The unisteer is similar to a cross steer setup. This is about the only thing that would work well. IMHO