Starting in 01/89 the subframe/mounts changed to the newer style.
I've never seen an 89 with yellow connectors, people have said over and over that they exist, but I don't believe it.
From all the 89's I've seen and/or worked on, they were all exactly as the wiring diagram showed.
I think people get confused when they see a production date of like 09/89 and then it has the wiring for 1990, when it is of course a 1990 model year car.
If anyone has a 1989 Supra with yellow connectors on the ECU, post a picture of the ECU showing the part number on it, as well as the data tag. I doubt a single person can provide this.
Yes the 89 model year was different than the pre-89 and the newer cars and is usually best treated as it's own year, but there is actually very little variation between different 89 cars.
Jeff