I don't think I have ever flown a GR with the Kruegers enabled and the F3 was built without them. However, it is possible to fit nib antennas above even fully-functioning Kruegers (shown here extended at 116 deg, with the black RF transparency above):
If you want really big forward antennas then you can fit an assembly that completely replaces the original flap/nib structure, as per the Tornado ECR.