In the course of doing some other work, I came across this poor installation of a ceiling fan. This was done when my house was originally wired by "professional" electricians, and presumably inspected under some version of the NEC, while being constructed in North Carolina in 1987-88.
As you can see, they simply lag-screwed the fan to the ceiling framing (a piece of 2x8 between two joists). The fan canopy trim (removed for photo) encapsulated the wiring from underneath, but above it was directly exposed to the wood and virtually in contact with it. A 14/3 cable was passed through a hole in the 2x8.
Obviously this is an egregious code violation and I must install a fan-rated ceiling box. But I'm not sure how to connect the fan to the box. Its mounting system is very different than the usual ball-and-socket system I've see in recent years. A pin between two brackets (sticking up from the fan housing) holds a rubber bushing of sorts. A u-bolt type thing (kinda like an upside-down "omega") wraps under that bushing and is lagged to the wood.
Just screw the u-bolt into the fan box as usual, except the spacing between the lag screws is 2-1/2" which won't match holes on any fan box of which I'm aware (probably will use Raco #295 "pancake" box).
Remove the fan, screw the box to the wood, and then re-attach the fan just as it was before, with the lag screws passing through holes I'd drill in the box. I believe that with metal boxes it may be acceptable to have metal passing from the inside to the outside of the box. OTOH, I'm making a modification to a listed box.
Hope the manufacturer can help me with an old-stock mounting bracket of some kind. But the fan is 30+ years old. It's one of those old Hunter ones with a heavy cast-iron housing, so I hate to simply replace it.