Specs for Hammond NSQ4008?

[basinstreetdesign]

Hi, I'm trying to measure low-level distortions on my HP 3580A spec. analyzer.  However, when I connect it to any other piece of gear on my bench I get significant amounts of 60 Hz power line harmonics mixed in with the test signal.  This can happen when connected to any of several other bits of gear such as my Tek465, my cheap Fluke counter or the UUT.  I think it's the result of a ground loop around all of those pieces of gear.  The 3580A was marketed with a transformer input as OPT 2 but mine doesn't have it.  I want to break the loop but still measure my signal.  So I am planning on putting an audio transformer on the front connector of the 3580A.  I want to use the one pictured below, a Hammond NSQ4008, but I cannot find a pinout or any specs no matter where I look.  I want to use this one because:

a) I have it,
b) it's renowned for fairly good quality,
c) it's not huge and
d) I have it.

Does anybody have any tech info on this transformer?