If I be not mistaken you were probably looking at a Stopler cab. I think you had to have the ROPS and roof for the cab to work.  In my opinion, if you wanted a cab, a Hiniker would be a better option. It is all one piece (more or less) and doesn't have the ROPS supports sticking up through the cab. These guys might have something you could use. Know nothing about them except what I see on their web site. Also, check eBay.

  http://www.knights-tractor.com/attachments-and-components/