That was also when they were still being made in the states, IIRC after the production went south so did the quality. There is an old thread concerning this somewhere.
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If you have a bit extra cash, I recommend picking up the coarse DMT 325 plate. It's perfect for lapping. I picked up one along with my Norton 4/8 and am so glad that I did. I use it every time I hone because its excellent at getting the black "swarf" marks off of each side of the Norton. Just a few figure-8's does the trick. Also ensures the hone is nice and smooth on each side. Definitely recommend. If not, the glass and sandpaper trick works too.