May be i have missed this in the forum, but can we not use the B777 for P3D V5 which is what i have?

Very easy to use it in P3dV5. All you need to do is:

1. Run the installer but point it to your P3d V5 directory instead of the V4 directory...

2. Go into you DLL.xml file under C:\Users\"PC Name"\Appdata\Roaming\Lockheed Martin\Prepar3dv5\ and add the following lines:

<Launch.Addon>
    <Name>Captain Sim Sound</Name>
    <Disabled>False</Disabled>
    <ManualLoad>False</ManualLoad>
    <Path>Captain_Sim\bin\cs.sound.dll</Path>
  </Launch.Addon>

After that you should be good to go! Please note I am not officially with Captain Sim just another customer like you; and this is not officially supported but it works... I was flying the 777-300 in V5.4 just a day ago.. And as always remember to temporarily turnoff any anti-virus / windows defender software you may have while running the installers... Once install is complete be sure to turn them back on. Have fun!