Get some wet dry 600 grit sand paper and use the short diff half to ensure the drive rings are flat. sand in a figure eight and do both sides of both rings. This will ensure the diff balls have a consistent surface and makes for a much smother diff. Also it doesn't have to be so tight as before the rings were smooth. there is a vid somewhere of Jiles Groescamp rebuilding a 416 diff. You might want to check it out.