Mystery machine

 I believe a very short lived LeTourneau design. A picture from a group of LeTourneau file phots, provides a clear view of RD4 with the unusual design from 1937.

Hi, Folks.
From the which brian18a has posted, it looks to me to possibly be a variation of the varying diameter pulley that LeTourneau used on his cable operated scraper ejectors to maintain a constant spring pressure on the ejector return rope. It appears to have the lift rope from the blade going to a smaller diameter pulley on the side of the larger pulley.

Just my 0.02.

Thanks fellers. I was beginning to doubt myself when CrawlerAddict asked what I thought it was! Hey, Mr. C.A., just how many RD4's will you own now? Our editor should have gone directly to you for all the photos! Saturday meeting might really be a tractor intervention for some folks...hehehe.
I am proud to say that with Eric tapping into a new honey hole, he is going to have more iron than me very soon. Rumor was he bought a bigger trailer so he can "poach" them in fewer trips! Great find sir. Can't wait to see all of them in the future. JM

Thanks to everyone for the info and to brian18a for the great vintage photo. 
I won't mention any names but someone who has become known as the "Enabler" has been helping to feed my addiction. Unfortunately I will never have as much iron or the variety he does, but I  can still try! Looks like I'm going to be dragging these all back home over the next week. When I do I will post a bunch more pictures of the unique sheaved one.
JM it is true, I have invested in a much bigger trailer and better truck to hopefully become a safer addict 😆

CrawlerAddict 

The enabler, eh? I can't imagine who that might be that doesn't run a fleet of trucks moving produce from here to there : )

I "resemble" that remark...Hah! Maybe I will get myself a dog too. I think Chrissy the pooch whispers in your ear while you are sleeping...BUY MORE TRACTORS...
Glad to see someone share the hobby with so much enthusiasm! JM

What this looks like to me is, another method of increasing the line pull for the blade lift rather than using the multi part block used on most cable blade lift assemblies.
It looks like the cable coming off the CCU attaches to the larger sheave, and the blade is connected to the smaller one, notice there is not the usual two part block assembly used to accomplish the speed reduction and increase power to blade lift.

What this looks like to me is, another method of increasing the line pull for the blade lift rather than using the multi part block used on most cable blade lift assemblies.
It looks like the cable coming off the CCU attaches to the larger sheave, and the blade is connected to the smaller one, notice there is not the usual two part block assembly used to accomplish the speed reduction and increase power to blade lift.