Yes, it is one hole offset, with a y-pipe. 4" y-pipes are for 4" systems, and the 5" y-pipes are used for the 5,6, and 7 inch systems. The stacks on the 6 and 7 inch systems are reduced down to 5" o.d. to fit into the the y-pipe. Pictures? Well I've got lots of pictures, I will try to attach them!
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I have got some more, but they need to be resized!