JD 4000 mmm deck compatibility

[shooter1873]

I have a John Deere 4300 compact tractor. I bought a JD 4000 mid mount mower for it and it doesn't seem compatible. The mower deck serial Number is LU0072B180409 made in Moline Ill. Now I've read on the web that there are two different 72 inch mmm decks and only one will fit the JD 4300. Do I have the wrong deck? If so, what do I need instead? Any and all help will be greatly appreciated. Thank you very much. Mike

 

[shooter1873]

PS The above described deck is 72 inches.