John Deere 4052R Cab,, Deere 855D UTV, Z920A Zero Turn Mower and assorted implements
First place I'd try would be Original Cabs (do an internet search for the web site)
Then, just do a search (Google) using "Compact Tractor Cab" as the query.
These Laurin cabs are really nice. I've never had one on my tractor as if I get a cab I get factory but I've operated a 110 TLB with one and they are just like a factory cab.