Then it must have been a 450.
Yep, I think you have come up with enough.
It was a 1971 450 Ducati Desmo, commonly called the "Silver Shot Gun".
I haven't owned another bike that vibrated as much as that did, it boiled batteries when given a few revs and would snap engine bolts every time I took it out, cracked the taillight off and dangled by the wiring.
Your go.