Serial # 5321.... Motor came with a boat I purchased. I thought the shifting and linkage was was just off a spline . It shifted through the gears but it did not feel right. I took the unit apart and found the shift cam, reverse gear and clutch were bad. Trying to look up parts I realized it was not the original lower unit. It seems a mix of shift mechanism, clutch and gears did not match any diagram for any newer, older, bigger or smaller gearcases I could find. The closest I could get was either 150 xr4 magnum or a XR2150HP. It has the preload pin and a nut on the driveshaft. The casting is 1647 6670 . I came upon another lower unit which is casting # 1647 9197. As I move along on the project there will be more questions. For now : The 1647 - 6670 and the 1647 9197 casings appear to be exactly the same from the outside. What is the difference between the two ? Were the original internals the same ? My 1647 6670 casing is in good shape. the 1647 9197 has been coned and has a low water pickup on it. It is also broken at the vents above the prop where the two attaching bolts would go. I hope to switch the internal. .
