Those'll work far better than those you linked from Ebay! I bought ofna diffs from a guy on UE for $80 - same ones UE includes in their 6 spyder Ultralights.

After you get diffs and pinions, find some shims and set them up right. If you've never done it, go over to UE and find their setup instructions for theirs - well documented, lots of pics, and easy to understand. Once you see these, you'll know what need to do for yours.