That's a 502 EQ. The 103 is a "Zero Amp" Mixing Amplifier, according to the info I have here. Generally, you'd find the 502 sitting in the feedback loop of a 101 or 110 amp card. I know pretty much nothing about the 103 beyond what I mentioned above.
You can find a bit more info here and elsewhere with some digging. Also, there's the new Spectra Sonics.