Yanmar SD20 Saildrive Drive leg structural faulure

[Janaucamp]

Dear fellow mariners, I need some advice and help here. I noticed that the sail drive was loose and dry docked my catamaran to have a closer look.
After removing the sail drive I saw that the leg cracked in two. Photo attached. There is no evidence of impact whatsoever. The drive was serviced about 2 months ago and worked about 110 hours since then. There is no damage to the propeller and the A and B diaphragms are in perfect condition. I have no idea how old the sail drives are. They are powered by Yanmar 3YM30 machines. No over revving on my watch. This is a sailing vessel.
Is this a structural failure? Metal fatigue? What happened here?
I'm in Mozambique in a small town called Quelimane right now.

[Janaucamp]

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