JD 425 mower decks

[JDLX178]

I've been researching 425's since I am in search for one and have found the weight of the available decks for it. I've seen 48" (175 pounds), 54" (185 pounds) and 60" (300 pounds). This may be a stupid question, but are these correct....and if so, why the huge difference in weight between the 54" and 60"?

Thank you in advance,
Paul

 

[94BULLITT]

Thicker metal in the 60 possibly?