[Bigdav160]

I seen that floor change on this forum before. Looked like a lot of work. There is a cross member where the original third seat rear feet attached. I'm not sure about securing the front.

On a side note, my '65 Town Wagon was originally a three seat SUV. It used some type of hook and pin to attach the seats to the floor. The rear two seats are missing but the pieces are still in the floor. I don't think they are attached to a cross member at all, just the plywood.