Have you got a standard front differential or have you upgraded it to a 3.54 from a defender, discovery 1 or Range Rover classic?
If your Salisbury axle is a pre stage 1 axle it will be a standard series ratio at 4.7:1 and will be fine if used with the standard front axle.
If your front axle has been upgraded to a higher ratio then you will have to change the front to a standard 4.7 ratio or upgrade the Salisbury to 3.54 by using parts from a defender Salisbury axle.