On the GR3
Before mounting the nozzles the engine access covers are removed again.
using a marker pen to make the mounting face hidden when the nozzle is fitted
then the heat shield is glued in
and the nozzles. These have tabs to clip onto the mounting plates, but I have sliced the off and glued them in place to make alignment easier. although these will rotate I have elected to fit them permanently in the rearward orientation.