The one on the left is correct , that is the one referred as a crankback, the one on right is a semi-automatic and will only work on later pumps...there is a difference in the wheel holes and the faces will not interchange. The semi-auto came out in the late 50's in the 1066 Bennett, 39-A Tokheim 300 Tokheim..Totalizer wheels, bell and face mount "bar" are the only parts on those two computers that will interchange.Of all the computers I have had my hands on I have only seen about 4 of the 4 wheel computers...
Joe
