Cat 1/2 for my tipping box?

[blunosr]

Hi, I have a 2005 Kubota MX5000 and the book says it is category I/II. I am in the process of making a tipping box and need to know how wide to make the lower links.

Cat 1 is 26" wide, Cat 2 is 32.5" wide. What should I do?

It will be mostly used for firewood gathering, but sometimes I might put a water tank on it.

Thanks,