[Milsurplus] Waterboy System?

[Tom Norris]

I have a VLF receiver, marked "Vlf Receiver/FDD"
with many similarities to receivers several folks have
found that are labeled as a "Unit of Waterboy system."
The ID label is missing on mine other than the bit
with the s/n (20). Covers 1 through 600 KHz.
My unit matches the form factor of the HF rx found
at http://www.roveroresearch.com/ss_ba/r1451.html
and is quite similar in appearance.

The modules are marked "Sylvania" as well, but the RX
is unmistakably Watkins-Johnson.

Anyone have any info on this system or care to make
SWAG's, etc?

Tom