That is beyond cool, congratulations on a great find!
When that young fella gets a little older, find a copy of the book "Bulldozer" by Stephen Meader and read it together. It"s the story of a young man and a D2 set in Maine right after WWII and it is just great. I read it for the first time when I was about 15 on the recommendation of an uncle and found my own copy, still read it once in awhile today, thirty years later. He wrote several books about adventuresome, hard-working young men and they"re all good.
Sorry for the hijack- once again, thanks for the story and pictures.