This topic is pretty well spelled out, with lots of pics at:
http://machines.hyperreal.org/manufacturers/Moog/Modular/The short story is that Ic, IIc, IIIc are the earlier console cabinet models
along with their "portable" bretheren the Ip, IIp, and IIIp. The numbered
models came later with the 10 and 15 in the portable versions and the 35 and
55 in the console cabinet form. There were some really early console
modulars that went by System 1, System 2, etc.
Note that there are very few "stock" Moog modulars since, like any good
modular, they were customized either from the start or added to.
Eric
> I've never got the hang of that Moog way of numbering models.
> Is it IIIP =
> three portable cabinets; 35 and 55 = 35 and 55 modules respectively?
>