Here we have an early 1970’s 85-105 hp Chrysler 2 stroke Outboard Lower Unit May fit other models as well. Lower unit turns and shifts very smooth. Gear oil looked good, there was no actual water in it, just a mild string of moisture. We recommend replacing the impeller and seals as we don't know when they were last done. The drive shaft has 15 splines and measures approximately 23-1/4" from the top of the water pump housing. This is for 20" transoms. Has the 18 spline / pin drive propeller shaft. This had doel fins on it at some point, so if you want to use them it already has the holes. Fresh water use only. Good replacement lower unit. See pics.