Prop shaft thread dimensions

[airshot]

My old Minn Kota model 65, 36# thrust trolling motor broke the prop and prop nut ( plastic). Figured on replacing the nut with an aluminum or SS nut. Search d everywhere and can't find the thread specification on the shaft, not even on the MK website. Must want it kept a secret....anyone know what the thread spec might be ? 3.25" dia motor housing.....thanks

 

[lckstckn2smknbrls]

Do you have the broken nut? Do you have a set of calipers? Measure the shaft and count the threads per inch.

 

[airshot]

With some experimenting I found it is a 5/16" fine thread ( 5/16-24) . the plastic nut broke into numerous pieces, SS on their now....thanks