[Milsurplus] ?? on USN type MN-5

[Hue Miller]

At this last hamfest i bot a US Navy type MN-5, actually 2 of them,
with handset, control box, outside speaker horn. This seems to be
an FM transceiver by Link Co. operating in the 30-40 MHz range-
i believe. This operates off 125/1/60, the power cable has an AC
plug at the end, altho i don't know if AC power was the original 
setup. Seems kind of strange to have something in an ATR box
that does 125/1/60. My question is, what was intended role of this
equipment? With the outside speaker, i assume ship use? Also,
what is actual freq range & power?
Hue Miller