Here's 2 ordinary Hemingray-45s, but they are my oldest and my newest! The one on the left was made in 1938 and carries the date code 12-38 with no dots after the 38. The one on the right is marked 38-50 : : : : : : : : (16 dots meaning the year 1966). There is only a slight difference in the mold profile between the two pieces. The 1938 piece has a very faint icy gray-green tint, and 1966 piece has a light yellowish-straw tint. For a bit of perspective, if you were born the exact day the first one was molded, you waited until you were about 28 years old before the one on the right was made! If anyone has found other Hemi-45s with 1965 or later date codes on them, drop me a line! Especially wondering if Hemingray CD 155s exist with a 1967 date (the last year of Hemi insulator production).