i was having performance problems boat not getting up to speed.86 searay with a 5.7 liter and mercruiser sterndrive.Finally came down to the wrong ratio in the upper drive unit.So i ordered a new one with a 3 year no fault warranty.So this morning i go and install the upper drive unit only to find out that the lower input shaft splines is worn hard.So i installed the new upper drive.i want to make sure that was my problem before spending money on a new lower unit
