By year I don't know which instrument any LBC has. For electric tachs, look on the face of the gauge to determine if it's RVI or RVC type. I am guessing that a '65 would be an RVI electric tach. These are current sensing. I have an email acquaintance who has tested and set his calibration by using a modified 60hz wall-wart transformer. The web site where this information was posted is down for the moment. I'll make a mental note to look for it later and post a link here when/if I find it.