The H model had tail numbers of 66-16### in 1967,and 1968 were factory H models. Most of the ships were H models by the time I got to the flight platoon in March of 1968. I think we may have had one or two but they were gone by May. Some of the rebuilds we received in later 1968 were converted D models. The only way you could tell was the patch on the nose compartment where they moved the air speed indictor tube to the roof. I know that some of thing parts we received were left over from the D model. If you replaced the sound-proofing or the seats sometimes they didn't fit quite right because they were for the D model and not the H.