OK, here is the top of the CD 145 HGCo's. The order is different than the last picture. The one on the left is the one on the left in the last picture, and the two to the right are switched. The left one has a H on the dome that does not line up with the embossing on the skirt, as you can see. The one in the middle, the insulator with the larger embossing, has two very small H's on the dome which line up with the embossing on the skirt. The right insulator has the same size H as on the insulator on the left, but it lines up with the embossing on the skirt. I know there are many variations with embossings with other insulators, but I didn't know a CD 145 HGCo had variations like this. I thought it was pretty straight-forward compared to a CD 121 Am Tel. Does anyone know about these like if they were made at different plants, different years, ect.? Any thoughts are appriciated.