A lot of people don’t understand. Just because something was first built in some year doesn’t mean something with the same basic airframe couldn’t be built decades later.
The C-130 is a prime example.
Yes...I hope I clarified that point in post 66
Yes, what Szonian is saying is that while the airframe design dates to the 1950s the aircraft currently still in service were actually new build airframes in the 1980s. Totally newly manufactured aircraft updated and call the TR1 at that point and time.
So, the design is 60+/- years old but the current aircraft are about half that age.