Believe it or not, the term Translon as the translational unit predates Walter Gilberts 'Exon' (1978). In 1973 Suresh Goel had a letter published in Nature arguing for the establishment of units of Transcription (Transcon) and Translation (Translon). www.nature.com/articles/245...
Transcription Unit - Nature
Nature - Transcription Unit
nature.com
I think my favorite part is that it rhymes with "exon"