[time-nuts] Help ID'ing Frequency Standard

[John Ackermann N8UR]

Looking through the junk box I came upon a metal box labeled:

Frequency Standard
05110-6014
Series 330

It's about 4 1/2 x 5 1/2 x 3 inches and has odd voltage inputs -- -16V, 
+10V, -12.6V along with a terminal for "meter switch" and 2 BNC jacks. 
There are several adjustment points accessible through the box.

Google doesn't turn up anything.  Anyone know what this beast is?

Thanks!
John