I think that Synth Tech MU modules were in Other/Unknown because they never manufactured any MU modules. Any of the ones in ModularGrid are DIY hacks by individuals, at least that I can recall. I'm not saying to do it one way or another, I'm just saying. ;-)
Actually, is there a MG rule on that? I'm never sure if I should put a module that was DIY'd into a different format under the manufacturer of the "guts" or if it should be under Other/Unknown??