Bolt Size on Paragon Transmission

[cenger]

Can anyone help me with the thread size of the gear shaft coupler on a paragon transmission? My recollection is that it is 3/8 fine thread but the bolt does not spin right in and I don’t want to force it. Is there a special thread type needed?

[tph]

3/8 fine is the correct thread. Try running a tap
through by hand first. Just might have a burr.
tom
vintage marine