[Milsurplus] TBY With Handset?

[David Stinson]

Been watching Ken Burns "The War" series.
Episode 2, documenting the battle for Saipan,
there is a scene with a Marine using a back-pack
mounted TBY.  He is not using the standard-issue
mike and headset, instead using a handset similar to that
you see on the SCR-195 and the SCR-300.

I know from a photo taking in Italy that an SCR-194
(BC-222), which was also supposed to use the 
headphones-microphone rig, was used with the 
handset (probably from SCR-195)  and I have a
BC-222 Signal Corps modded to take the handset
from SCR-300.  
Has anyone ever seen any documentation of this
modification being applied to TBY?

73 Dave S.