[Fulltiming]

There was at least one 1974 serial number ending in 6H that had a Cat 3208 210 HP diesel installed at the factory. 1H and 1G had a CAT 1160, 4H had a Cummins 555, and 17H had a Cummins 903. In 1975, 2J had a Dodge 440 gasoline,1038D36 5J had the Cat 1160, 6J had a Cummins 555 replaced with an International 9L, what I believe is 8J had a Cat 3208, and 36 had a Cummins 555.

Unless the Serial Number plate has been replaced, it certainly looks like your came with a 3208.