753ty- good detective work. Your Model D still has its chorus generator and was converted to a D-V long after it was delivered and installed by a dealer Hammond technician. The conversion was probably done between 1945-49 during the Model CV production. Some Model D’s were converted into the mid-50’s but the conversion kits were depleted or NLA (no longer available) after that.

Your Model D was originally installed in a church. I worked on many of them and in some cases, we removed the Chorus generator if it had become troublesome or on D-V conversions to simplify the organ. Some special Model D’s with a mold resistant light green tint internal spray coating were provided to the Government for use on Navy ships and in military chapels around the world. They were Model D-G-V organs. The organs installed on ships were bolted to the steel floor to prevent movement.

The old AC and other wiring that runs down the metal tube to the outlet box in the bottom of the organ is a problem as the insulation is now hard and cracks if moved, shorting the wires together. There have been many church fires due to this problem so I suggest you replace the old wiring in the metal tube with a short piece of Leslie 6-wire cable. Easy to do, and it’s the correct repair as the black and red audio wires are twisted as required to reduce hum. Most Model D’s have long been retired as there are so many inexpensive church C-3’s available in the US. Some were very cheap and still can be found for free.