Cody & Amber<br />Serries 400 used on 4 cylinders up to 1985. Serries 800 used on 6 and 8 Cylinders up to 1985. After that OMC went to the cobra outdrive. I not sure what year the Serries 400 started but my 1980 is a 400. Plate on mine on the Starboard side of the outdrive not too far from the ball drive.