Because of the long coulter beam in the front I'm almost totally sure that it is an F125 4 bottom made into a 3 bottom by cutting the box tube and putting the tail wheel on the 3rd bottom.
The front coulter leading so far forward on the 4/5 bottom plows keeps them from being used on 2 cylinder tractors.
The easy way to spot a 3 bottom F125 is by its smaller square beam. It has the same size beam as used on the F115/F120 plows. The F125 4 and 5 bottom plows used the larger beam as seen on this plow.
Also note that the line of draft is different for a 4 bottom F125 than it is for a 3 bottom. It will not draft correctly. The 1250 works fine by just cutting it off from 5 bottoms all the way down to 3 but the F125 is a different story. The cut off 125's will wear the landsides and continually pull the frontend into the plowed ground. I know because I've owned two of the cutoff F125 plows. They just dont work correctly.