Be sure and follow the instructions for replacing water pump in the FAQ’s at top of page by Sherm. You have to get the splines for the drive shaft lined up and……also……the shift shaft lined up. The driveshaft will line up first, then the shift shaft. Ounce the driveshaft lines up the case will slide up a bit further and you reach around to front of gearcase where the shift shaft is exposed and wiggle the shift shaft in place. Yes, a helper is nice plus the gearcase is heavy. Don’t try to force the gearcase with the four nuts and bolts. If you can’t do it by hand you prolly don’t have it lined up correctly. If you force it by torque, prolly breaky something.