This gasket came with a 1979 Jeep CJ5. You must take your time and install this gasket properly to keep the AMC 20 differential from leaking. All surfaces must be surgically clean and smooth, meaning more than 40 years of moisture and corrosion have been removed. The original style cork seal was intended to be used with a lube where I used a slightly tacky adhesive to hold the cork in place. Torque the bolts to 10 ft-lbs and then 20 ft-lbs following the greaser sequence. Absolutely no leakage or seepage. Instantly fillable and no RTV required!