If you are wanting to keep your exhaust more to the original type, then this OEM Quality 1500-1600cc Bus Muffler will get you started in the right direction. Your bus will look and sound like it did when it was born.
This stock style muffler comes painted in gray primer that will burn off in time. It has one outlet on the driver's side.
Don't forget to purchase the needed gaskets and kits for installation.
Note: These can be used on a 1974 Thing if you attach the damper pipe and leave off the tailpipe.