I just finished my auto to 5spd swap in my 85' 4runner, i got an ECU from a 5spd same generation. . .plugged it in and it runs like a top. I have read quite a few times that the ECU for the auto will richen your fuel mixture and throw codes. . . and also i noticed my auto ECU has a couple of additional numbers that differ from the 5spd ECU besides the main part number. I only had to splice a few wires under the hood none in the cab.