This is an interesting one!
As has been said, the R&P will need to be able to travel in the same arc as the axle to avoid bump-steer.
It follows that with the R&P attached to the axle, a slip joint in the steering column will be required to allow for the movement of the axle.
A U/J of some sort willgive you this movement, would have to be heavy duty for a truck though?
As for a suitable R&P, get a tape measure and go to the breakers (salvage) yard. I personnaly don't like the idea of altering steering components, so I have always tried to match up lengths/dimensions etc with something that I can 'just bolt on'. Fabricating mounts/brackets is fairly straight forward, you just need to be sensible and bear in mind the weight of the truck and the forces involved.
Hope this helps
Taff
