Ok, so I am pretty sure it is 3" all the way through. I can post a picture if you want, but there is a number 3 on both hubs. I didn't see any other text, although the pipe that runs down through the slab is embossed with the words "permanent pipe."
Now, not sure if this matters, but it is unlikely all of this will ever be going at the same time. Also, we have a new high efficiency washer.
Any thoughts?