Excellent Quality Double Lip Oil Seal. I have Used This Seal For Years And When Properly Installed They Will Not Leak. I Use a Little Liquid Pipe Sealer On The Case To Help Seal And Add Some Lubrication When Pressing In. I Also No Not Use The Cork Or Small Tab With This Double Lip Seal. Check The Main Gear Spacer That The Seal Rides On. If The Back Of It Is Chewed Up And Not Smooth You Will Never Maintain Your 125-135 ft lb Clamp Load On The Sprocket Nut. This Will Lead To A Loose Nut And Seal Leakage.
Fits The Following Harley-Davidson Models
1936-1948 Knucklehead
1937-1948 Big Twin Flathead U Models
1948-1964 Panhead
1966-1979 Shovelhead