>>23400806
Haze'n-thley was planned during Haze'n-thley II's development as a way of using these upgrade parts to modernize Hazel too. Following the naming convention, the TR-6 model is marked as "II" and by extension the TR-1 unit doesn't have the number. In this case don't think of them as necessarily sequential, just maintaining consistency with the pattern.
Shrimple!