I have a Fisher Baby Bear in my shop and cannot find a elbow that will fit into the rear exit. It seems that the exit is exactly 6 inches and all the pipes I can find are exactly six inches. Any ideas how I can make it work? I have all the black pipe and stainless pipe for through the roof just need to find a elbow. I had purchased a T connector and that will not fit and I purchased a black elbow from Lowes and that will not fit either. Need some advice ASAP. Thanks!