This is a new very high quality and very nice amp gauge. This will fit the MB, GPW, CJ2A, CJ3A and CJ3B. It is a 2" gauge and will fit the gauge panel in the M38 and M38A1 if you are using a 12 volt system. This gauge will work just fine with both 6 and 12 volt electrical systems. I have personally used these on my restorations, both 6 and 12 volt and never had a problem. Since this an electrical item there are no returns.   QTM Parts