I don't actually have the original connecting pieces. The previous owner used some modified tent poles. It would be easy to make some out of some round tube and just flatten the ends.
As far as I can see, there would be 4 pieces and they bolt through holes in the hoops, pictured below. I would think they would all be the same length.
Cheers, Murray
https://www.aulro.com/afvb/images/im...009/09/698.jpg

