I hope that Rick does not mind if I add to his response-
You have a Sherman Combination transmission. Three ranges, high-direct-low. The Sherman Combination transmission was a dealer-installed option prior to 1957. After 1957 the Combination transmission was available as a factory-installed option.
Thing that throws me is your serial number. The number you give, 861790, is way too high to be a Golden Jubilee/NAA serial number. Way too high. The serial number on the GJ/NAA is a sequential production number (one, two, three, four, etc.). Ford only produced 128,965 model NAA tractors (Golden Jubilee Fords are model NAA).
At first I thought "hey, he has an 861," which is, were I to opine, the pinnacle of Ford tractor development during the 1950's (translation: he likes the 861). I was really trying to read your serial number as "861" before "790" (model designation before sequential production number), but (a) the 861 has a five-speed transmission, not a four-speed, and (b) the starting serial number for the x01 series Fords is 1001.
Could you be reading the last digit incorrectly? Is it possible the "0" is actually a diamond (indicating cast-iron cylinder sleeves)? This would drop the sequential production number (serial number) to 86179, which falls right into the 1954 model NAA range. To be a Golden Jubilee (model NAA) Ford tractor the serial number has to be below 77475. The serial numbers on both Golden Jubilees and NAAs begin with the prefix "NAA."
Who cares about the serial number, but it would be nice to know what you have, wouldn't it, if just for parts, capacities, and such. ID'ing your tractor, be it a GJ/NAA or Hundred series Ford, is really pretty easy. There are several fairly obvious differences, if you know where to look. I can tell you where to look. Better yet, I can show you. Clicking here will take you right to a Web page that illustrates, using photographs, the differences between the GJ/NAA and the Hundred series Fords.