If I'm not mistaken, the leaky diff issue was the S5 o-rings. They were too small. If you buy new seals, they are thicker than the old ones. I have a older prospec that I updated to a R and notice this when I was rebuilding the diffs. You shouldn't run across this unless you get old stock of S5 o-rings. Only other cause of leaks was stripped threading in the diff case itself not allowing the ring to tighten down correctly on the gasket.