JD140400: I purchased and installed the Curtis Cab on my 4500, plus, for a about $350.00 extra bucks, I purchased and installed the 20,000 btu heater on it too. It uses coolant from the engine to warm the inside of the cab. There is nothing like clearing a driveway with the wind blowing and staying warm. Heck, when I first used it, I forgot I had it on and I couldn't figure out for the life of me why I was sweating. Believe me, when it's 10 degrees outside with a 20MPH north wind, you don't mind clearing the yard of snow.
To install the Curtis Cab, get a buddy or family member to help out or have a shop do it for you. It is heavy and takes a couple of people to lift some of the panels. The doors remove easily and the windows swing out for summertime use. Because I have had cancer, I have to be careful of how much sun I get so the roof couples as a nice sunroof. Good luck!
Roger