OK, so I got the belly mower off and inspected. Blades look decent and while I have 2 sets (three blades, each) headed this way from Kubota, I'm going to leave the one installed on it a few times.
Similarly, the belt looks a bit work but not too bad and while I've received two, I'm going to go with the installed belt for now. Someone selling a belly mower reached out saying he had pictures but I've not heard back. I'm just interested in having it as a spare.
Finally, I've decided to buy a 60in flail mower. I'm realizing what D2Cat is saying, since the same mechanism raises and lowers the belly mower as the flail, and you can't run both at the same time, then when the flail mower is down in position for mowing, then the belly mower is also down and dragging through the vegetation.
So unless I'm missing something obvious, this means the belly mower must come off before using the flail. Sorry for the rookie questions.
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John