for a diesel vehicle with ice cold air you should purchase a Ford truck with the powerstroke diesel. You can make it like a meat locker inside of one of them.
I would go with the 300D if you want the diesel MB. I have just gotten the a/c in my project 300D where I can live with it (in middle Georgia). When it is 95 degrees F outside I have 55-60 degree F air blowing out (134a conversion). I have made some modifications to the way the system works and with the a/c button mashed most all of the air comes out of the two center vents and the vent on the left side of the steering wheel.
Jim
'85 300D
'95 E320
'97 CRV