Help identifying blade (possible D4 - D6 size?)

This blade came with my D4 7U but I believe it isn't original to that type of tractor.
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[*]the C frame is very heavily built
[*]the mould board is a little over 3m wide
[*]the width at the trunnion caps is right to fit my 7U 
[*]if it had a serial number I can't locate it (possibly underneath one of the the stick rake mount plates?)
[*]seems to have mounts (that have been cut off) to suit rams on the nose of a tractor
[*]the brackets for rams attached to the track frames appear to be a later addition

Paul.
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Thats a D4C or D4D set up with some modified braces welded on.

Hi, ROME K/G.
The D4C had the blade lift arrangement mounted on the outside of the track frames like the U series and earlier and the lift points on the C-frame would have been just behind the middle angle brace points on the sides of the C-frame.

It does appear that something has been cut off the front of the C-frame on the back face of it either side of center, which would be consistent with a D4D with the lift rams mounted on the hard nose.

Hi, Haus.
If you are lucky, there could be a serial number stamped into the BACK of the blade below the rake mount on the right side. You may need to scratch some rust or paint off to find it.

Just my 0.02