The original metal hoops are 20mm x 3mm material and I used M6 nuts and bolts. It really isn't that critical, the strip of steel I used was just what I had to hand and is a bit larger than original but you get the idea. With a cut the hoops will bend enough to allow the propshaft to come out. Agreed that a new top hoop with a single nut each side would be a neater solution but this works, it doesn't hit the cover and you don't use it often.
