78 may be the last production year for big blocks, but they were used through the early 80's in motorhomes. I have a friend with an 81 motorhome and he told me it had a 440. I argued that it couldn't be because of the manufacture date of the unit, but sure enough, it is a factory 440 in a 1981. A Chrysler parts manager said that the motorhome companies bought truck chassis in bulk and had them sitting on their lots to build. Therefore many motorhomes were built in the 80's using older truck chassis and engines and titled them in whatever year the motorhome was built. So, if the op says he has an 80's motorhome with a 440, he has an 80's motorhome with a 440.