I’ve replaced the bearings before while doing a gear case fix (not transmission) but it was a few years ago and I can’t remember the sequence of what comes apart first.
You mentioned the transmission but that might just be a naming issue. The transmission is behind the friction disk drive plate and does not get removed for a wheel bearing replacement.
The wheels ride on an axle that goes through the gear case on one side (the left) and a 7-8 inch long dog bone shape flange on the right. Both are inside the tractor housing. There is a cover plate (13) and I forget if it was on the inside of the tractor base or outside. If the plate is outside and a hole there big enough the bearing might come out that way. But the bearing may be frozen into the long flange holder. If no hole or frozen in then you’d have to remove the long flange to get the bearing out.
To remove the long flange you have to remove quite a bit, most of what is in the friction disk diagram, friction disk axle and components. But you might be able to back out (4) the friction disk shaft and leave most of the other stuff in place if you get lucky.
If you have to remove all shafts in that drawing it’s big job but doable and no special tools needed. A pin punch set helps (available at Sears for about $20) but not essential. For an average person who works on home equipment it would be something to tackle over a few days.
Go slow, have a camera and take pictures at each step. Have a pen and paper there to make notes of the sequence of removal no matter how much you think you’ll remember it later. Sketch the parts as they come off especially washers and collars. Have a number of cups or small boxes around so you can group parts as they come off. Number them so you can grab the right parts in order which will remind you how they go back together versus have all the nuts and washers together.
As I mentioned if you’re lucky you may just be able to replace the right bearing without too much disassembly but if you do both then the gear case will have to be opened and that requires removing all the shafts in there so the full job. All in all the drawings are not familiar to you and look more intimidating that the actually work. The problem part is what order things come off in and that becomes apparent as you go and not a big deal. If you keep track of the parts and take some pictures and notes and group the parts the re-assembly will be fairly straight forward.