Failed fisherman
New member
My father n law let me borrow is 7.5hp thunderbolt. Lower unit started grinding. I cant figure out how to remove the drive shaft and get I to the propeller gear area (clutch dog) I found a donor motor with no spark but good lower end unit to swap. I cant figure out how to look up the serial numbers to see if they will work together. They are both 7.5 thunderbolt short shaft. Serial number on mine which runs like a top is 4254128 and the potential donor motor serial number is 3376122. Many thanks in advance. I work out of town all week and on the weekends all the shops are closed to bring this thing in.