Yes, I've searched. Keep reading. In the FD section there's this thread-

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/1993-front-harness-annotated-connector-pictures-892648/

I've searched for something similar in the FC section, but can't find anything like it. Yes, I've found wiring diagrams and such, but nothing as simple and cut and dried. I realize there are various differences in harness between S4 and S5, TII, NA, etc. But why not have one definitive thread for each/all? Or is there one somewhere and I was just not able to find it?

 

There isn't a thread just for that (to my knowledge), but the link in my sig. will take you to a thread where I covered the emissions harness wiring differences for S4 NA -> S4 TII and S5 NA -> S5 TII swaps. If you want info on the differences between series, compare ECU pin outs in the S4 and S5 FSM fuel and emissions sections.