First off, AERCO is: Acme Electronic Robot Company. One man operation, guy's name is Jerry Chamkis. Google brings up loads of funky stuff he's into (catching gamma rays from outer space, and running them through a synthsizer to produce weird ass sounds). I don't know if he still will make them, but he recently serviced mine and told me as long as he's alive, he'll keep them going for us.
I'm pretty sure each one is a custom unit, because I also have an MP2 (verified by the label on the inside of the unit) and it's a bit different from what Goose said his is. Mine looks a little bit like the first pic. but has XLR (M) outputs, instead of RCA's. Mine has a stepped gain as follows: 26db, 28db, 30db, 40db, 50db, 60db (or so the label on the top says). Mine also has a 4-pin XLR already rigged into it for external power. I only use the internal 9V option when stealthing, as they are a BITCH to get in and out.
FWIW, I've been told, mine at least, has Jensen transformers and futhermore I've been told that Jensen and Reichenbach are one in the same.
All I know is is sounds damn fine with my 4022's, it did sound fine with my old Earthworks as well.
Tim, seein' how you're a member of Team Upstate, if you want to borrow mine for a bit, I can send it out. PM me for details...