series three axle problems

ive just purchased an axle for my series three, ive since found out that the one i bought is from a series three lightweight, does anyone know if the diff ratio's are the same or if the lightweight one is compatible.

i seem to remember something about the lightweight ones being narrower

Only differance is the halfshafts which make it slightly narrower as the drive member is just a thin flat plate. Fronts have short drive shafts bit like later cv joint type. All the rest is interchangable. Lightwieght halfshafts are dearer so tend to get swapped for normal series type when they break.

thankyou for your help