There are four 12mm head bolts that hold the bearing support into the cases, you can see two of them in your pics. There are also four torx head bolts that hold the bearing retainer plated to the middle gear support. When the middle gear support breaks, usually, the case breaks where the inner two bolts attach, these are the two bolts that can be seen in your pic.
If you need anything, I have billet middle gear supports, and have OE Yamaha parts at significantly discounted prices.
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