Given Chris' [id=116188777; nice photo] I was able to create this overlay. Neither of the insulators were scaled in size, just outlined and positioned on top of each other.

You can see the smaller dome and the less flair in the skirt that is characteristic of the WT CD 153. Note that the cross section drawings in the Price Guide are more like the CD 153 Brookfield shown in the picture I listed above. The shape and dimensions of this WT piece are not quite similar to the drawing, so this reference of two actual insulators is probably more accurate.

Thanks Chris for providing your excellent photo of the two pieces.