OK one more time.
It isn't that I don't want to give you the numbers, I will. But the question is about physical differences in the 3 years the Originals were made.
One is clearly stamped 4377.
The other one is stamped 2566. Or 25661. That unknown number if that mark is a number, throws the date off quite a ways.
BUT if there might be another number after the 2566 which makes it a serial number in the 5 digit range and not 4 digit range. It is hard to tell on the casting if it is a number or some shape on the cast housing.
Therefore, if someone could throw out an opinion about the dates by the appearance of the steering adjustment opening, or the absence of a creeper hole, or anything else, then I would have something else to judge it by.
What I was told by my visitor is the 2566 should have another number because it should not be older than the 4377. That opinion was made by the physical appearance and his impressive knowledge of these tractors.
I read Ken's book. As detailed as it is, and with the wealth of information this forum has provided over the years, I didn't think this would be so hard.
I"m sorry I can't make this any plainer.