Changing the rear end over

Thanks , The third member appears to be just a standard diff, spider gears in the middle. He got himself a pretty tight rear. almost no backlash. So it wasn't abused. The guy gave him a pair of Srange axles too. A lot bigger around. If we have the rear narrowed the original axles , at the splined end become smaller as you move to the outer bearing. So I'm curious as to how they're going to re spline the axle if it is smaller in diameter. The stange axles are almost an eighth of an inch bigger in diameter. that would be doable I think.