Okay, JDM stands for Japanese Domestic Market, got it. Which apparently means that it was a Japan-only feature, part or vehicle.
USD stands for United States Distribution, or something similar. Parts, etc., available in the States.
Most of the "JDM" (which I originally thought was a brand name, yep, noob here!:oops: I learned mechanics with 460 Ford engines wearing blowers and twin carbs, so turbos and AWD are still a bit new to me!) parts I find online are engines/transmissions or front clips. Where can I find other parts such as the wicked vented rear taillights on the '93 JDM GT4 (or whatever label it wears in Japan)? Can the local Toyota dealership order JDM parts?
Also, what were the differences (other than right-hand drive and the taillights) between the JDM and USD 90-93 ST185's? Pictures would be helpful and greatly appreciated.