I have a John Deere Bagger Chute that I acquired through another purchase that I don't need.
The chute is 40-47 inches long depending on where you measure it from tip to tip/end. The shoot opening diameter is 7-7.125 inches where it attaches to the bagger unit. The bottom end of the chute where it attaches to the mower deck has an opening of roughly 13.25 inches x 5.25 inches.
I have attached several pictures for you to examine. Let me know if you're interested.