This looks like an early design drawing for GM in the early '50s, the actual outcome would have been like the '55 GM Scenicruiser pictured below (4105?). The regular version in this era was a GM 4104, Starting in... I believe '55 and running through '60. These would have had the 6V-71 (318).
My Coach is a '61 GM 4106 (the 50th one) made from '61-'66, and the Scenicruiser through this span was a 4107 and 8V-71 powered (568). The late '70's version was still much like mine and the scenicruiser was a 4905.
Not sure how many of you besides Bob are familiar with the Detroit, but I really like the sound of these things. I also bought Dad's HD20 Allis dozers from our Trust, and these have 6-110 Detroits, that is a 660 cube 2 stroke diesel, huge power for it's day. The blade on this is over 15' wide.
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'55 GM 4105..?
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'57 Flxible
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'61-'66 GM 4107
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'77 GM 4905
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