This is rather niche, but on the off chance that anyone cares, see the following.
If anyone has the Flight1 GTN750 AND any of the following addons from Area 51 simulations....
OH-58
B-2
RAH-66 Comanche
...I have modded the cockpits to include the GTN750 unit.
I recommend backing up the panel.cfg files for each aircraft before making these modifications!
OH-58:
Replace the existing "gauge04" line in the VCockpit01 section with this:
gauge04=F1GTN!GTN750VC, 407,9,365,362,UNIT1 //center diplay
B-2 Spirit:
Replace the existing "gauge01" line in the VCockpit01 section with this:
gauge01=F1GTN!GTN750VC, 558,493,298,302,UNIT1
RAH-66 Comanche:
Replace the existing "gauge08" line in the VCockpit01 section for both the Recon and Attack helicopters with this:
gauge08=F1GTN!GTN750VC, 49,530,337,415, UNIT1
Enjoy!
If anyone has the Flight1 GTN750 AND any of the following addons from Area 51 simulations....
OH-58
B-2
RAH-66 Comanche
...I have modded the cockpits to include the GTN750 unit.
I recommend backing up the panel.cfg files for each aircraft before making these modifications!
OH-58:

Replace the existing "gauge04" line in the VCockpit01 section with this:
gauge04=F1GTN!GTN750VC, 407,9,365,362,UNIT1 //center diplay
B-2 Spirit:

Replace the existing "gauge01" line in the VCockpit01 section with this:
gauge01=F1GTN!GTN750VC, 558,493,298,302,UNIT1
RAH-66 Comanche:

Replace the existing "gauge08" line in the VCockpit01 section for both the Recon and Attack helicopters with this:
gauge08=F1GTN!GTN750VC, 49,530,337,415, UNIT1
Enjoy!