Hi. mog5858.
In Eric Orlemann's book, "Caterpillar Chronicle", he mentions that Buster built a Siamese pair of Allis Chalmers tractors before he built the first twin D8s and I have seen video and photos that seem to indicate that there were two of these jiggers at Garrison Dam based on two different appearing front blade lift frames. One had rounded top corners above the raditors while the other had square top corners.
I also remember reading 'somewhere' - just where, I can't remember - that Buster had nothing to do with the Garrison Dam rigs.
And I suspect that all those who would know are no longer here to tell us, one way or the other.
Here izza link to a conglomeration of videos on Youtube complied from old movie films of the clearing and construction of hungry Horse dam in Montana - 1948 - 1954. there is about 4 seconds of the twin D8s at about 15.13 in the video.
https://www.youtube.com/watch?v=SvMO49Dbe-c&t=901s
And another on Veoh with the same 4 seconds at about 1.52.:
https://www.veoh.com/watch/v29408183beMJc4Gr
And a couple of attachments;
[attachment=69360]Popular Mechainics August 1950 Capture_1A - 2018-06-16_6-55-38.jpg[/attachment][attachment=69361]Popular Mechainics August 1950 Capture_1 - 2018-06-16_6-55-38.jpg[/attachment]
And a Youtube video of an old-timer telling of his days on the South Fork of the Flathead river before and during the dam construction. I only found this video after I had originally posted this reply and so I came back and added it.
https://www.youtube.com/watch?v=EP97zZPVPXA
Just my 0.02.
