I just got mine today, and I disassembled the entire thing to see what's what.
It's wired Pin3 hot, so yes certainly was a product of the US from the 1970s.
Funny about the 'poor man's dbX' idea, it really bears no resemblance to a DBX comp, from what I was able to discern. Looking over the PCB, it seems to be a FET limiter which uses a peak detector.
I used it today on a mix and thought "poor man's 1178". I did a quick comparison to my Dynamite (2) on overheads, and the MXR was fantastic.
All of the amplification is 5534s, and there is a very long TI chip called the TL336 CN. This seems to be the led meter driver.
I can't say. The board is a bit hard to trace.
It links really well.
Do you have a manual?