Nemeth Designs H500D Amphibian mod for FS2004. The original MD500D is not required.

Install:
-copy the "h500dwater" folder to your "FS9\aircraft\" folder
-copy the "Md500d" subfolder in h500dwater folder to your "FS9\gauges" folder. If original md500d addon is installed it may ask to ovwerwrite, choose yes.
-if everything's fine it works  