'late' 91-09 conical style. Note: The 86-03/10-up style is preferred by many for better flow characteristics. Note: The 91-09 late style is a conical (tapered) shaped gasket that was introduced by The Factory in 1991 and replaced, again, with the early style in 2010. Note that the early style will fit all models and is generally seen as the better gasket design.