Apparently, I checked a database I have access to and they were ordered new by "Wards Jet Freight" in 1978 and delivered in 1979. My involvement with them was for a few years in the late 1980s. I did maintenance training with Flight Safety in Tuscon and they had never heard of the mod for the emergency exit in the roof - the instructors were all ex factory guys. They also had 36 inch wide cabin doors, apparently 24 inch wide was standard - or perhaps more usual.