Can you not just bolt a piece of thick chain or a metal bar from one side of the tunnel to the other?? This achieves the requirement of the CAMS Scedule J does it not? I cannot see why have all the extra weight of an actual loop other than it probably stops a broken shaft from shafting teh underside of the floorpan/tunnel.
Was just going to use flat bar ($1.50) at the point where the centre bearing on a 2 piece prop went.