In 1940, IHC built 92,085 D series trucks. These numbers were built between January and December of 1940. I have tried to attach a picture of the production numbers. I hope this is readable.
Here is the thing. Rarity is nice, but this brings a greater difficulty of finding parts. When a greater number of a model are built, it is reasonable that a greater number will survive. Since there are no reproduction parts, one must rely on another truck being sacrificed to put life into a similar model. If you have a "one off", think about it, where will the parts come from? Can you say panel beater? Just about any fender or body panel can be reproduced with an English Wheel and a Yoder Hammer. but it could cost thousands of dollars for one piece. One of the body shop guys I had the pleasure of working with has the above tools and in his retirement does custom panel beating. He only charges $150 per hour for his time and the materials are extra. He is crazy busy.
When he and I were still working together, I built a custom side-cabinet for his toolbox. The adjustable shelves were built around the dimensions of his tools. The top roll out shelf and cord retractor were for his espresso, cappuccino maker.
Anyone with anything more than a passing interest in these IHC truck should drop a few dollars for a copy of the book I pictured in a previous post.
http://www.books4cars.com/