Gear Ratio

I am trying to find out what the gear ratio is for the upper unit on a OMC 5.7, cobra model 985690. I need this so I can purchase the proper bottom to match the upper. Thanks in advance for any help

I think gear ratios in the upper are different for 4 / 6 / 8 cylinder.-----Lower ones in an " 800 " drive are all the same.----Your location ?

Hi Thanks for the quick reply, I am located on the east coast of Canada. I have a 1989 Bayliner 2655 Ciera wide beam. Two years ago my bottom of the OMC Cobra outdrive failed and the Mechanic I used at the time replaced the bottom with a bay King cobra. So now I have a Cobra upper and a baby King lower. Ever since I have had RPM and power issues. After multiple troubleshooting fixes that did not work, I am convinced it is due to the mismatch of the upper and lower of the outdrive. I want to swap it back to just a regular Cobra bottom but I need to know what upper ratio is to match it. So I need to know what the ratio is to look for the corresponding bottom. The upper has a number stamped on the plate stating that the model is 985690 ENG 5.7/8L