[Milsurplus] T-17 variant or mod ?

[Hue Miller]

I have a T-17-B microphone with a plain, unfinished
aluminum "collar" around the microphone element
speaking area, with what looks like room for a standard
F-1 carbon element and a punched metal grill with a lot
more holes than the standard T-17. This does NOT look
like a hammified unit. Was this some kind of aftermarket
user modification?  The cord is grey - don't know if that 
is original either. -Hue Miller