Driveshaft loop prototype

I'd be interested if you can offer some detail. I need one for a '69 Charger with US Car Tool subframe connectors and a GV overdrive so I think it would need to be wider that an A body to reach the connectors. Can you give me upper hoop section dimensions so I can make sure it fits in the tunnel further back? Can it be made to B body width or is it already pretty universal?