I am not sure Les as I haven't pulled the back plate and measured differences, but they will be different. My initial joy that the flange to flange measurements were the same on both diffs was lost when I pulled out the flange shafts from both diffs. The old one (both RHS) was longer in the diff (see pics; old one on top and new one below) and new one shorter. I assume that will be the reverse for the LHS ones. So it seems I will need to get new axle shafts that have a 6 bolt pattern - that is using the drive flanges that came with the new diff - and that are the same length as my existing ones! Damn! Spline counts are the same.
