Ultegra RX and GRX compatibility

[Gummee]

To answer the specific question: I'm leaning towards maybe to probably not. Try it and see. I don't think anyone's actually tried to change the cage between the two.

I was told by someone (at Shimano?) that the GRX has the XT clutch in it vs the Ultegra RX's something else so something tells me they're just different enough to be a problem. ...but I've been known to be wrong before

M