Bill,
Thanks for the correction. The code posted by Chris matched an Exterior Color Code; and, as you say, there was no info on 1956 trim codes in the 46-72 ID Numbers book.
234N looks like an RPO code (on all Advance-Design trucks, 234 was the RPO number for exterior color, and the suffix-letter was the color indicator).
234N was also the RPO for Ocean Green in 53-55. In 1956, the interior color "Crest Green" was the same mixing code as the exterior "Ocean Green".
Tim
