There's a discussion of this vehicle on a military vehicle forum that you might find interesting. http://g503.com/forums/viewtopic.php?f=24&t=244639 I can't tell from the video you posted if the drive sprocket still has the original three toothed sprockets on each drive hub, or only two like the one in the Overloon Museum, (I'm guessing that sometimes they were replaced with Easy 8 ones because the regular Sherman track was more available than the unique M6 track). The M6 was built by Allis Chalmers, which didn't really strike me as interesting until I saw a photo in the Hunnicutt Shermn book of an Allis Chalmers prototype for the M4 Sherman that has those same spoked bogie wheels.