I dug around and found a new old stock muffler that's always made me curious. Inlet diameter is 2.890, inlet height is about 1.5 at the shortest point. outlet diameter is 2.441. Outlet height is 4". Body height is right about 9", body diameter is about 7.750. Has Nelson 8V79 stamped on it. Inlet and outlet are oriented about 90 degrees apart.
I'm going to go out on a limb and say this is a 1550 utility muffler.