Batboard

What are the main differences between the Model "AN" "BN" "CN" and "DN" MT2000 UHF Radio's? I have an "AN" Model what am I limted or Not Limited to from the latest model revision?

Thanks In Advance

Also any good sites to buy replacement parts for these radios? Cases, knobs, stickers etc..... I have found that ebay is hit or miss.

AN/BN/CN/DN are just releases
New boards, more reliable, fixed this bug and that bug, new seals etc.etc
in reality from a user point of view very little