[Milsurplus] " M-1 " on BC-453

[Hubert Miller]

Looking from the rear of the BC-453, down at the dyno mount studs, I see the rearmost left stud and the frontmost right stud have thin metal straps which also attach to the chassis.
I do not recall seeing this before, but it has been many actual years since I last looked at any Command Sets receiver. 
When I first saw the M-1, I guessed it was probably the static drain resistor, but I don't recall seeing it on any other Command receiver I have viewed. 

I guess I'm now in the market for a plain alu top cover including tube hatch cover and screws, to restore this otherwise unhacked receiver. Would buy a junker for these parts,
Also a plug adapter for the front, but I know those aren't growing on trees ( anymore ). 
Hue,

>I have the manual revisions up through 1956, and "M-1" is not mentioned.  So I have always assumed that "M-1" came later.  But I believe that it involved installing thin brass straps across the four receiver dynamotor shock mounts on BC-453-B's.  I don't recall ever seeing the straps on anything other than that receiver.

Robert Downs