440226 looks like the model number. The model number starting with 440 means that it is a 1965 to 1968 4400, which is the utility chassis variant of the 3 cylinder 4000 series, which was made from 1965 to 1975, but they switched from using the number 4 to the letter D part way through 1968, so it can't be any later than that. That is the heavier fixed width front axle of the 4400 in your first picture. The first 2 means that it has a gas engine, and the second 2 means that it has transmission driven PTO (on-live PTO). The 6 at the end is incorrect, as the last character should be a letter which would designate which transmission it has, and your description sounds like a power reversing transmission, so that last character should be an F, not a 6, but there may have been another variant of the power reversing transmission that used the letter G, which is easier to confuse with a 6.
The serial number C138327 is a 1966 serial number, from near the middle of the year
That third number, 7007, is not a valid production code.
There should be another number on the left side of the transmission on the same flat spot, which would be the production code for the transmission itself. If you can find that, post it and we can tell you when the transmission was assembled, and the tractor was probably assembled a few months after that.
The serial number C138327 is a 1966 serial number, from near the middle of the year
That third number, 7007, is not a valid production code.
There should be another number on the left side of the transmission on the same flat spot, which would be the production code for the transmission itself. If you can find that, post it and we can tell you when the transmission was assembled, and the tractor was probably assembled a few months after that.
