There is one rack & pinion setup that will work by Unisteer, it mounts to a regular Vega steering box mount and only works one side of the rack which attatches to the right side steering arm. It still requires use of a normal tie rod.
Regular racks wont work with a solid axle UNLESS it is mounted to the axle, but then you would need some sort of flexible steering shaft since the rack is moving around with the axle. I have seen this done on boggers using an old Pinto flexible steering shaft but these aren't street vehicles so I don't know how safe or reliable that would be.
If you were to mount the rack to the frame, the toe in / toe out would be changing every time the axle moves up and down - that would result in a dangerous and scary ride at best.....