Seems you are not the first to confuse the later BX with the early models on category 1
Category 1 is very, very common and typically you're gonna see Category 1 on tractors under about 50 horsepower. The back of this B-series tractor here is a Category 1 hitch. It's gonna have five-eighths holes in it. Now, there's one caveat inside of Category 1 where you may notice some sub-compact tractors being listed as limited Category 1. Kubota's early BX series were done that way, today's are full Category 1, there's some other competitive sub-compact tractors that are limited Category 1. And, what that limited part is telling you is that because the hitch is low to the ground, it may not be able to lift as high or open as wide as a full Category 1 hitch. So you can find some Category 1 implements that are not gonna work properly on a limited Category 1 tractor.