Hi, Avatar. Just an informational comment, and certainly not cutting on your battery charger in any way. I wonder if someone perhaps switched in a replacement ammeter years ago. I believe the ammeters on the old tube-type battery chargers could easily get fried, when the rectifier tube failed (shorted internally). Back in the day, mechanics and garage people made do with what they had around, and probably wouldn't have spent the money to obtain a "factory replacement" ammeter..
The Ford ammeter (made by Hoyt) currently in place on your charger is most likely from an automobile or truck. You'll note the meter face shows both charge and discharge, rather than just "charge", as we'd expect with a battery charger ammeter. Hoyt is based in New Hampshire, and began making electrical instruments of all kinds in the early 1900's. Many were used in radios and cars in the teens and 1920's. And, many of their panel meters of that period used the same three-hole mounting pattern. I believe the company is still in business. John
Last edited by Jolly-John; Sun May 12 2019 07:39 PM.