I think it would be nearly impossible to put a rack and pinion on a straight axle. I can't concieve of a way to avoid bump steer if its mounted on the frame, and how would you connect the column if its mounted on the axle.
Axle mounting the rack seems the easiest way to avoid bump steer. But once you solve the steering column issue you've now added 50 to 100 pounds to your unsprung weight, which means your handling and ride have been hurt.
I don't think its a good idea. If No Limit has overcome the issues I'd love to see how they did it.
