Tom,
My internet has been down this spring a lot. It is working again for now.
Here's a pic of my 1952 S Case with eagle hitch. It is hand written on the build card "Eagle Hitch" I believe the Eagle hitch was put at the factory in 1955 when this tractor was sold. It came from a Case dealer in Algoma Wisconsin who said he special ordered the S with eagle hitch. According to my S and D series parts books the eagle hitch parts are the same for both series. A lot of the eagle hitch parts are different from the S and D to the SC and DC tractors. The drawbar frame, draft arm brackets, lift rods and draft arms are all different.
The first pic is my '52 S, the second is a SC/DC arm next to the S arm. Both of my S arms have been bent slightly and need straightened about an inch or so.
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Here's my '52 DC
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Here's the special D and S draft arm brackets that raise the arms higher.
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Here's the SC/DC draft arm bracket
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Tape measure showing lifting point and eagle claw measurements on my S
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Measurements on a spare SC/DC arm I have
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I have seen 2 DI's with eagle hitch parts the same as the SC/DC tractors. These DI's had lift rods that were welded making me think maybe someone had put SC/DC parts on them.
Hope this helps, Nick