Usually the gear oil will push the grease out of the speedo adapter. One end of the speedo adapter has a screw with a seep hole, the grease will get pushed out, and gear oil follows. If driving in the summer for extended periods, it can move a decent amount out. I took mine apart, and found one goofy U shaped seal, someone said there was an O-Ring in there, but I didn't see it. Does anyone have a line on these seals? I suppose checking the case vent is a good idea as well, it might be pressurizing the transfer case. After a long drive (60+ miles at 55mph) my speedo adapter (I think it is) starts squealing due to lack of grease. At least thats my guess, the noise is coming from that area, and only happens when the truck gets above 10mph, and has been driving for an extended period. Keeping ones truck ahead of the maint. curve is a never ending battle...