I would suspect that the tilt/trim portion would be similar for most of the larger Yam engines.
As I recall (and this was just from perusing the shop manual, so I wouldn't swear by it), the level is determined in much the same way as the LU fluid is: i.e. you fill to the filler plug level. The system is supposed to self-purging; with a few up/down cycles, the air gets moved to wherever it is that doesn't bother operation (though on my F115, it took quite a while - a few weeks - to get the weird graunchy sounds to stop. Didn't really affect operation, just sounded weird.)
If you have no leaks, I'd see no reason suspect a low level rather than first suspecting air where it shouldn't be. See below on purging and filling, though.
The cylinder uses gneral hydraulic fluid, as I recall. If you don't get confirmation, I'll try and look it up later. From what I've seen, Dextron II Automatic Transmission Fluid is a viable alternative.
Here's a post on your problem form another forum: