If the tail moved, the LSD was working. If one wheel stood still, the other one would just roast and the tail would go nowhere. My '87 560SEL had the LSD factory with about a 2:48 gear. Sometimes I wonder if it would be a good swap to get the revs down a bit at 65-70 mph. Since my '86 SDL was built for the US market, it was built with 55mph in mind, not our current higher limits. Does anyone know what an SDL would come with in Europe? I'm thinking the German market version would have had the 2:48 gear. Interesting idea, I think.