spacer in differential carrier

I emailed Dr. Diff about it when I put my Greens on and it's sort of a situational answer. I ended up not taking them out of my rear end (clutch type), but I'm also running stock axles, so Dr. Diff said it wouldn't be an issue. I think someone else hit it on the head that the aftermarket axles are usually longer for more spline mesh area. I just didn't want to lose the little things if I even went back to a tapered setup, so I left them in, but if you have greens installed you don't need them.