Another picture of the CD 143.4 American, this time from the base. To the left is a CD 145, that appears to have been made in the same mold. Note the small glass line in the pinhole at about 2 o'clock on both insulators (it appears to have been made by a defect in the mold). Careful examination of the outside surface confirms the mold to be the same, so I'm guessing the difference was made by changing only the mold part that formed the inner skirt to one that did not.