It will NOT work. Contrary to popular belief, there are many harnesses over the years. Unless you are good with wiring, and ready to make things work, you should get the proper year harness. You can use an auto harness in a 5-speed car, but there are differences between the years. 86-88's are pretty interchangeable I believe, but there are changes between 88-89 and 89-90. I'm not sure, but I believe it changed again between 90-91 then stayed the same for 92. There is a sticker near the ECU end of the harness that has the part number on it. You should try to match it.
Edit********I re-read your post. There are actually two different 89 harnesses at least. Early 89's had the yellow plug harness like the 88. If the 89 harness is yellow plugged, it should work.