1961 Navigator roadholder fork cotter pin

Terry,
Are you referring to a pinch stud and nut?

There are two of these on the lower yoke that secure the stanchions. 

One on the left fork slider that secures the axle. 

Not aware of any cotter pins. 

Peter

There are no 'cotter pins' (wrong name). There are two studs in the bottom yolks with nuts to retain the stanchions. and the bottom left hand fork leg has another stud into the aluminium with a nut that If overtightened brakes the fork leg.
As far as I am aware this design was the same throughout the Roadholder life.

Pinch clamp studs (2 off) Part Number 16164   -  7/16” (20tpi) x 2” x 5/16” hex nuts.
I believe the threads at both ends are the same.ie.  20tpi.