I looked at the first page of the thread quite carefully (I hope!) and tried searching and browsing the rest of it.

I couldn't find any information about the 763 with 25J and 188Y. Air Canada admits to the existence of this version in the second diagram from the left on its page of 763 seatmaps.

I booked a flight (not at ac.com) and selected 17F, which implies the intended aircraft must be the 25J/188Y version, since this seat doesn't exist on any of the others.

Any words of wisdom about this particular aircraft? Sadly a J seat is not an option for this particular flight, so I'd be more interested in learning if 17F is actually a lavatory, doesn't recline, has spikes in it, or is reserved for lunatics only