Had some trouble trying to id a transmission case for a Harley Davidson Panhead and wanted tp share this incase any one else has trouble to Id case. This pretty much is it. It is for Knucklehead transmissions also. Types of transmissions for Panhead and Knucklehead. Vent hole location for Panhead and Knucklehead transmissions is the key
Type 1: 1936 - identified by only having the 4 mounting studs holding the transmission to the frame. The 5th mounting hole located under the kick starter does not exist on these transmissions. Additionally, there is no boss for this 5th mounting point cast into the transmission case. I believe a bracket was used between the kicker cover studs and the frame in 1936. Additionally, this case has no vent boss cast into it. The vent boss is normally located on top of the case just forward of center on the kicker side. During these years the transmission vent was located on the kicker cover.
Type 2: 1937-1939 - identified by having no vent boss cast into the transmission case. The vent boss is normally located on top of the case just forward of center on the kicker side. During these years the transmission vent was located on the kicker cover. Five mount points on all cases 1937 and later.
Type 3: 1940-1955 - The transmission vent has now been relocated from the kicker cover to the transmission case. There is a vent boss cast into the top of the case just forward of center on the kicker side. It is drilled and tapped for a vent screw (not one of the screws that holds the transmission top in place).
Type 4: 1956-1964 - The transmission vent boss is still cast into the case (top of case, forward of center on the kicker side) but it is no longer drilled and tapped for a vent screw. The venting is not achieved using one of the screws that secure the transmission top.
