The arm is a "Proaim 7000". A friend of mine bought the whole "Flycam Fluojo" set on eBay, which I have been pretty leary of, but it's actually quite solid--they've taken a lot of cues from the higher-end Steadicam systems, even if some of the execution is a little off.
The arm is almost a cross between the Flyer/Zephyr arms and the G-50/G-70's, and works pretty well as yet, but the Flycam vest they provide is a nightmare. Again, it takes cues from the Steadicam vests, with the ability to clamp down to provide that extra snug fight (which is much more than I can say for the Glidecam X-22...ugh) but the design does not fit a human well, and the socket block is pretty much fixed where it is--you can't drop it lower to the waist because the waist-band clasp gets in the way.
The arm feels very solid, and works well with the system, despite some things that simply aren't making sense. Perhaps it's because they're not Steadicam operators, or they just copied what Steadicam has done without understanding why.
So my hope is that Flycam would be willing to knock a few hundred dollars off the price if I don't get a vest from them, and I can find a real Steadicam vest somewhere online or on this forum, and start building my rig piecemeal. If I had the money, I would go right out and buy a Zephyr (well, if we're dreaming, I'd rather get a Clipper) but the market around here will not support the work I'd need to repay that amount of money in a decen time. The Flycam system is cheap enough that I'm comfortable spending the money on it, knowing that I'm going to be making severe modifications to it, but well built enough that I know it'll handle a lot of what I can throw at it.
But in order to know if I can do that, I'm looking for the socket block sizes, so I can measure my friend's Proaim arm, and determine I if I can start down this road.