I did a complete restoration of a 51 M-38 about 2 years ago. The owner was able to find all the parts through military suppliers around the country. Fortunately all of the charging system components were good. Parts were expensive but relative to other old cars & trucks, not so bad.
If it works fine, drive it and enjoy it. If at some point the charging system dies, it's not a major deal to convert to a 12 volt alternator, ignition system, etc.
Fred
