I forgot that I had these slightly used blades for my JD Hydro 175 mower when I traded it in years ago. I had replaced them with the “Gator” mulching blades.
19 3/8” long x 2 7/8” or 2 15/16” wide with a 11/16” hole.
The part numbers stamped on the blades are N83459 8L6218B.
According to our local JD dealer the new part number for similar 38” decks is AM141041.
Here is a partial listing of mowers that they will fit but apparently it will fit most John Deere 38" Decks.