I've always thought this was so interesting. Most of the drawings and information in Lynn R. Stuart's "Stuart's Insulator Guide" shows careful study and relatively meticulous attention to detail. This particular drawing shows an (apparently) non-existent deep amber Armstrong CD 154 (although Stuart doesn't use or mention CD numbers) but the embossing shown in his drawing has only been seen on the Armstrong CD 217, an entirely differently shaped insulator. Posting this here so everybody can see what was being discussed on ICON recently (Sept 2022).

There are several different CD 154 insulators hand-drawn in Stuart's book besides this one. Presumably drawn with pencil? Each of those illustrations are slightly different (each individually drawn, not exact duplicates of other CD 154 drawings inside the book).

I think the chances are 99.9% that this insulator does NOT exist, nevertheless, it still seems rather odd........ since Stuart seems to have been well acquainted with the attributes of the insulators he shows in this book.

This is from the Revised Edition (second printing) published in April 1970. This has a black cover with a drawing of a Yucca plant on the front. So, does his very earliest edition (apparently with a green cover) also have this on page 9? If someone lets me know, I will update this photo caption. Thanks!

UPDATE (September 29, 2022): I received an email from Liam Addams, and he informed me that the "Stuart's Insulator Guide" first edition does NOT include the deep amber Armstrong listing. He also notes that the insulator listings do not start until page 21. The BARCLAY insulator (drawn as a CD 147) DOES appear in the first edition but it is shown on page 37, not 17. (Thank you Liam for this information!)