My #3 answer was based upon the op using the words "upper class rigs". So, I suppose we would need to define exactly what he intended with that nomenclature. To me, upper class rigs are Prevosts, Newells, etc. and I think you'll be hard pressed to find a new one with an ammonia based refridgerator...and many of the old ones as they have been using residential fridges in them for quite some time now.
This design is now trickling down to even the mid class, coaches (as std equip) and even as options on the entry level coaches.
So, in retro thought, I suppose you could find an upper level rig with an ammonia based fridge....I'll change my answer to "yes".