Dave's got a great eye for detail! I had the same problem and called the guys at Just Rear Ends to ask about it. Their first question was "Did you use a layer of black silicone on the face joint?" When I told them I used the paper gasket they supplied plus the crush washers they said that those "...come from the housing supplier, and we never use them." On the Jeeps, which get their differential fluid changed more often due to water crossings, we always just use a layer of black silicone, no crush washers.