I have a couple sign shops here in my small town that could do it easily in vinyl so anywhere else could too all they need is a scale drawing or a decent pic or a scan of an existing decal. My decals are a YM3810 2wd and not a "D" but I am not so concerned as to have any made...yet.
Someday I plan on fixing the metal work properly thats under the shiny new paint and will go the extra mile and get proper looking decals made. They will simply scan whats on there now and rescale the scan and edit in a "d" and it will be between them and me so a secret in other words. fwtw