It can be a bit tricky that one. I'd suggest you put some sealant on there and tape it in place until it dries, otherwise you could end up with water entry if the grommet isn't well sealed against the metal.

Thank you for that tip & very much appreciated. have since done that. Thank God summer is around the corner .

The right way to undo the grommet is from the other side, rises down the roof a bit and undo it from there, otherwise 90% it will snapped or not hold very well and cus leaking.

Not without modification. The GXL has an incandescent light, which has a different connector to the LEDs fitted to the VX +. Richards are unable to find the correct plugs. So you can fit it, but you'd need to manually spice in to the light wiring rather than use the plugs fitted to the supplied loom.

Thanks Jamie, much appreciated

It's been in for over a year now. No water or dust leaks. All working fine.