[Milsurplus] Aircraft Beacon light bulb

[Skywarrior]

Hi All,
I am restoring a rotating beacon light that came off a CH-34 Choctaw helicopter.  I am in need of 2 of the beacon bulbs.  They are 28V are flat on the back with a buld in reflector.  The numbers on the base are as follows: FJ28V21CP.  It has a standard single connector on the bottom with offset tabs on the side.  I am sure it is a standard bulb, I just have no source here.
TIA
Bruce