Went out and tackled a decent hill for the first time in a while the other day, and the old girl was bouncing around a fair bit. Each time I hit a large enough bump there was this high pinch, sort of whining sound. It has not happened before or since, only happens when hitting a bump offroad. My first thought was the engine fan hitting on something.
But I've checked gearbox and engine mounts, they all look fine. Tried moving the radiator, it has no play in it. The shroud has a tiny bit of play in it but not enough to come even close to the fan.
I'm a bit stumped as to what to look for

It did sound like it was coming from the front but I've been pretty bad with picking noises in the past.
Is there enough body/chassis flex in these things to move the shroud ~2cm closer to the fan in rough stuff?
Anyone had similar noise come from somewhere else? Couldn't be anything in the driveline could it?