Anyone know the differences between a 2wd and 4x4 steering rack. Is it the ratio or physical dimensions?

Would fitting a 4wd (adjustable) steering column to a 2wd car work or would you need to change to a 4x4 rack and steering joint??

The reason I ask, is somewhere down the line my 2wd saff has had a 4x4 adjustable steering column fitted but its still running the 2wd rack and 2wd steering joint (rubber bush), and the steering has always been a little stiff. Wondering if this is due to the steering setup.