Siamese twin D8 bulldozer. 5:22 video:
https://www.youtube.com/watch?v=TSCBNylPbZA
Previously:
https://www.homemadetools.net/forum/...119#post172359
https://www.homemadetools.net/forum/...948#post133757
https://www.homemadetools.net/forum/...5477#post81955