Thanks for these replies. They tie in with what I understood. I was reading my '65 sales brochure last night and it struck me that the Catalina had the 3rd row option but not the Bonneville.
I hadn't looked at the '66 brochure so thanks Stuart. But it looks like the 3rd row if required could be incorporated into the '65 Bonneville using parts out of a '66
Cheers
Ian

